Class 10th Science Chapter 4 – Carbon and Its Compounds | Versatile Nature of Carbon – Tetravalency and Catenation

🧬 Carbon and Its Compounds

Versatile Nature of Carbon – Tetravalency and Catenation

Class 10 Science | CBSE + Foundation + Competitive Level

🔬 Versatile Nature of Carbon

1. What is the Versatile Nature of Carbon?

English:
Carbon is called a versatile element because it forms an exceptionally large number of compounds. The two main properties responsible for this versatility are:

• Tetravalency
• Catenation

Carbon also forms strong covalent bonds and can combine with many elements such as hydrogen, oxygen, nitrogen, sulphur and halogens.

हिन्दी:
कार्बन को बहुमुखी तत्व (Versatile Element) कहा जाता है क्योंकि यह बहुत बड़ी संख्या में यौगिक बनाता है। कार्बन की बहुमुखी प्रकृति के मुख्य कारण हैं:

• चतुसंयोजकता (Tetravalency)
• शृंखलन (Catenation)

कार्बन मजबूत सहसंयोजक बंध बनाता है तथा हाइड्रोजन, ऑक्सीजन, नाइट्रोजन, सल्फर और हैलोजन जैसे तत्वों के साथ यौगिक बना सकता है।

2. Tetravalency of Carbon | कार्बन की चतुसंयोजकता

Carbon has atomic number 6. Its electronic configuration is:

2, 4

Carbon has four electrons in its valence shell. To achieve a stable electronic configuration, carbon shares electrons with other atoms and forms covalent bonds. Since carbon can form four covalent bonds, its valency is 4. This property is called tetravalency.

हिन्दी:
कार्बन का परमाणु क्रमांक 6 है तथा इसका इलेक्ट्रॉनिक विन्यास 2,4 है। इसके बाह्यतम कोश में 4 इलेक्ट्रॉन होते हैं। स्थिर इलेक्ट्रॉनिक विन्यास प्राप्त करने के लिए कार्बन इलेक्ट्रॉनों की साझेदारी करता है और सहसंयोजक बंध बनाता है। इसलिए कार्बन की संयोजकता 4 है। इस गुण को चतुसंयोजकता कहते हैं।

3. Why Does Carbon Form Covalent Bonds?

Carbon has four valence electrons. It cannot easily lose four electrons because this would require a very large amount of energy. It also cannot easily gain four electrons because a highly unstable negative ion would be formed. Therefore, carbon generally completes its octet by sharing electrons. This sharing produces covalent bonds.

हिन्दी:
कार्बन के बाह्यतम कोश में चार इलेक्ट्रॉन होते हैं। चार इलेक्ट्रॉनों को खोना अत्यधिक ऊर्जा की आवश्यकता रखता है और चार इलेक्ट्रॉनों को ग्रहण करने पर अस्थिर ऋणायन बनेगा। इसलिए कार्बन सामान्यतः इलेक्ट्रॉनों की साझेदारी करके अष्टक पूरा करता है। इसी कारण कार्बन मुख्यतः सहसंयोजक बंध बनाता है।

4. Example of Tetravalency — Methane

Methane has the molecular formula:

CH₄

One carbon atom shares one electron with each of four hydrogen atoms. Thus, carbon forms four C–H covalent bonds.

    H
    |
H — C — H
    |
    H

Therefore, methane demonstrates the tetravalency of carbon. हिन्दी:
मीथेन का आणविक सूत्र CH₄ है। एक कार्बन परमाणु चार हाइड्रोजन परमाणुओं के साथ एक-एक इलेक्ट्रॉन की साझेदारी करता है और चार C–H सहसंयोजक बंध बनाता है। इस प्रकार CH₄ कार्बन की चतुसंयोजकता को दर्शाता है।

5. Catenation | शृंखलन

Definition: Catenation is the ability of an element to form bonds with atoms of the same element, producing chains or rings. Carbon shows exceptionally strong catenation. Carbon atoms can bond with one another to form:

• Long straight chains
• Branched chains
• Closed chains or rings

हिन्दी:
किसी तत्व के परमाणुओं का उसी तत्व के अन्य परमाणुओं के साथ बंध बनाकर शृंखला या वलय बनाने का गुण शृंखलन (Catenation) कहलाता है। कार्बन में यह गुण बहुत अधिक पाया जाता है। कार्बन:

• सीधी लंबी शृंखलाएँ
• शाखित शृंखलाएँ
• चक्रीय या वलय संरचनाएँ

बना सकता है।

6. Examples of Catenation | शृंखलन के उदाहरण

Straight Chain:

C — C — C — C

Branched Chain:

   C
   |
C — C — C

Ring Structure:

Carbon atoms can form cyclic structures such as benzene.

Carbon can form compounds containing a very large number of carbon atoms. For example, long carbon chains occur in polymers. हिन्दी:
कार्बन परमाणु आपस में जुड़कर सीधी, शाखित तथा चक्रीय संरचनाएँ बना सकते हैं। यही गुण कार्बन यौगिकों की विशाल विविधता का एक प्रमुख कारण है।

7. Why is Catenation Strong in Carbon?

The carbon atom is relatively small in size. Therefore, the nucleus can hold the shared electrons strongly, producing a strong C–C bond. As a result, carbon atoms can form stable chains and rings.

हिन्दी:
कार्बन परमाणु का आकार अपेक्षाकृत छोटा होता है। इसलिए नाभिक साझा किए गए इलेक्ट्रॉनों को अधिक मजबूती से आकर्षित करता है और मजबूत C–C बंध बनता है। इसी कारण कार्बन स्थायी शृंखलाएँ तथा वलय बना सकता है।

8. Carbon Can Form Different Types of Bonds

Carbon can form:

Bond Type	Example	Representation
Single Bond	Ethane	C—C
Double Bond	Ethene	C=C
Triple Bond	Ethyne	C≡C

This ability further increases the number of compounds formed by carbon.
हिन्दी:
कार्बन एकल, द्वि तथा त्रि-सहसंयोजक बंध बना सकता है। इससे कार्बन यौगिकों की संख्या और संरचनात्मक विविधता बहुत बढ़ जाती है।

9. Tetravalency + Catenation = Huge Number of Compounds

The combination of tetravalency and catenation gives carbon an extraordinary ability to form compounds. For example:

Tetravalency → Four bonds
Catenation → Carbon–carbon chains/rings
Strong C–C bonds → Stable structures

Together these properties produce millions of carbon compounds.

हिन्दी:

चतुसंयोजकता → चार बंध
शृंखलन → कार्बन-कार्बन शृंखला/वलय
मजबूत C–C बंध → स्थायी संरचनाएँ

इन गुणों के कारण कार्बन के लाखों यौगिक ज्ञात हैं।

10. Comparison: Tetravalency vs Catenation

Tetravalency | चतुसंयोजकता	Catenation | शृंखलन
Carbon has valency 4.	Carbon bonds with other carbon atoms.
It forms four covalent bonds.	It forms chains and rings.
Example: CH₄	Example: C—C—C—C
Related to four valence electrons.	Related to strong C–C bonding.

11. Why Carbon is More Versatile than Silicon?

Both carbon and silicon belong to Group 14 and show tetravalency and catenation. However, carbon forms much stronger and more stable carbon-carbon bonds because carbon atoms are smaller. Therefore, carbon forms a much larger variety of stable compounds. Exam Point: Carbon has a greater tendency for catenation than silicon.

12. Important Exam Concepts | महत्वपूर्ण परीक्षा बिंदु

🔥 Remember:

• Carbon atomic number = 6
• Electronic configuration = 2,4
• Valency = 4
• Group = 14
• Tetravalency = ability to form four covalent bonds.
• Catenation = ability to form bonds with other carbon atoms.
• Carbon forms straight, branched and cyclic chains.
• Carbon can form single, double and triple bonds.
• Strong C–C bonds are responsible for stable carbon chains.
• Carbon's versatility is mainly due to tetravalency and catenation.

13. MCQs — 30 Questions | बहुविकल्पीय प्रश्न

1. What is the valency of carbon?
कार्बन की संयोजकता क्या है?

A) 1

B) 2

C) 4

D) 6

Answer: C) 4

2. The property of carbon responsible for forming four covalent bonds is:
चार सहसंयोजक बंध बनाने का गुण है:

A) Tetravalency

B) Catenation

C) Allotropy

D) Ionisation

Answer: A) Tetravalency

3. Catenation refers to:
शृंखलन का अर्थ है:

A) Formation of ions

B) Bonding of carbon with itself

C) Loss of electrons

D) Gain of electrons

Answer: B) Bonding of carbon with itself

4. Carbon has how many valence electrons?

A) 2

B) 3

C) 4

D) 8

Answer: C) 4

5. Which compound demonstrates tetravalency of carbon?

A) CH₄

B) NaCl

C) H₂O

D) NH₃

Answer: A) CH₄

6. Carbon forms a large number of compounds mainly because of:

A) Metallic nature

B) Tetravalency and catenation

C) Radioactivity

D) High density

Answer: B) Tetravalency and catenation

7. Which type of bond exists between carbon atoms in ethane?

A) Ionic

B) Single covalent

C) Double covalent

D) Triple covalent

Answer: B) Single covalent

8. The bond between carbon atoms in ethene is:

A) Single

B) Ionic

C) Double

D) Triple

Answer: C) Double

9. The carbon-carbon bond in ethyne is:

A) Single

B) Double

C) Coordinate

D) Triple

Answer: D) Triple

10. Which property allows carbon to form long chains?

A) Catenation

B) Neutralisation

C) Reduction

D) Sublimation

Answer: A) Catenation

11. Carbon generally forms covalent bonds because:

A) It is a metal

B) It easily loses four electrons

C) Sharing electrons is energetically favourable

D) It has no valence electrons

Answer: C) Sharing electrons is energetically favourable

12. Carbon has electronic configuration:

A) 2,2

B) 2,4

C) 2,6

D) 4,2

Answer: B) 2,4

13. Carbon belongs to:

A) Group 14

B) Group 1

C) Group 17

D) Group 18

Answer: A) Group 14

14. Which structure can carbon form because of catenation?

A) Only ions

B) Only gases

C) Chains and rings

D) Only metals

Answer: C) Chains and rings

15. Which is NOT a typical structure formed by carbon?

A) Straight chain

B) Branched chain

C) Ring

D) Metallic lattice of carbon ions

Answer: D) Metallic lattice of carbon ions

16. Carbon can form how many covalent bonds in methane?

A) 1

B) 2

C) 3

D) 4

Answer: D) 4

17. Which bond is represented by C≡C?

A) Single bond

B) Double bond

C) Triple bond

D) Ionic bond

Answer: C) Triple bond

18. Which bond is represented by C=C?

A) Double bond

B) Single bond

C) Triple bond

D) Ionic bond

Answer: A) Double bond

19. Which bond is represented by C—C?

A) Triple

B) Single

C) Double

D) Ionic

Answer: B) Single

20. Which property is especially strong in carbon?

A) Catenation

B) Metallic bonding

C) Ionisation

D) Radioactivity

Answer: A) Catenation

21. Carbon can combine with:

A) Only hydrogen

B) Only oxygen

C) Many elements

D) No other elements

Answer: C) Many elements

22. Which factor contributes to strong C–C bonds?

A) Large atomic size

B) Small atomic size of carbon

C) Metallic character

D) Radioactivity

Answer: B) Small atomic size of carbon

23. Carbon forms stable chains mainly due to:

A) Weak C–C bonds

B) Strong C–C bonds

C) Ionic bonds

D) Metallic bonds

Answer: B) Strong C–C bonds

24. Which element is chemically similar to carbon because it belongs to Group 14?

A) Silicon

B) Sodium

C) Chlorine

D) Oxygen

Answer: A) Silicon

25. Carbon has a greater tendency for catenation than silicon mainly because:

A) Carbon is radioactive

B) Carbon atoms are smaller

C) Silicon is a metal

D) Carbon has no valence electrons

Answer: B) Carbon atoms are smaller

26. Which of the following is an example of a carbon chain?

A) C—C—C—C

B) Na—Cl

C) H—O—H only

D) NaOH

Answer: A) C—C—C—C

27. Tetravalency of carbon is due to:

A) Four valence electrons

B) Two valence electrons

C) Six valence electrons

D) Eight valence electrons

Answer: A) Four valence electrons

28. Carbon's ability to form branches is related to:

A) Catenation

B) Ionisation

C) Oxidation

D) Neutralisation

Answer: A) Catenation

29. The combination of which two properties makes carbon highly versatile?

A) Density and colour

B) Tetravalency and catenation

C) Melting point and boiling point

D) Magnetism and radioactivity

Answer: B) Tetravalency and catenation

30. Carbon is called a versatile element because:

A) It forms only one compound

B) It forms a huge variety of compounds

C) It is a noble gas

D) It does not form bonds

Answer: B) It forms a huge variety of compounds

14. Subjective Questions — 30 Questions | वर्णनात्मक प्रश्न

1 Mark 1. What is tetravalency?

Tetravalency is the ability of carbon to form four covalent bonds.
हिन्दी: कार्बन द्वारा चार सहसंयोजक बंध बनाने के गुण को चतुसंयोजकता कहते हैं।

1 Mark 2. What is catenation?

Catenation is the ability of carbon atoms to bond with other carbon atoms.

1 Mark 3. What is the valency of carbon?

The valency of carbon is 4.

1 Mark 4. How many valence electrons are present in carbon?

Carbon has four valence electrons.

1 Mark 5. Give one example of a compound showing tetravalency of carbon.

Methane (CH₄).

2 Marks 6. Why is carbon called a versatile element?

Carbon is called versatile because it forms a very large number of compounds due to tetravalency and catenation.

2 Marks 7. Explain tetravalency of carbon.

Carbon has four valence electrons and forms four covalent bonds by sharing electrons. This property is called tetravalency.

2 Marks 8. Define catenation with an example.

Catenation is the ability of carbon to form bonds with other carbon atoms. Example: C—C—C—C.

2 Marks 9. Why does carbon form covalent bonds?

Carbon has four valence electrons. Losing or gaining four electrons is energetically unfavourable, so it completes its octet by sharing electrons and forms covalent bonds.

2 Marks 10. What types of structures can carbon form due to catenation?

Carbon can form straight chains, branched chains and cyclic/ring structures.

3 Marks 11. Explain the electronic basis of tetravalency.

Carbon has atomic number 6 and electronic configuration 2,4. It has four valence electrons. By sharing these electrons with other atoms, carbon can form four covalent bonds. Hence its valency is four.

3 Marks 12. Explain catenation in carbon.

Carbon atoms form strong C–C bonds because of their small atomic size. Therefore carbon atoms can join with one another repeatedly to form long chains, branched chains and rings.

3 Marks 13. Why is carbon-carbon bonding important?

Strong C–C bonding allows carbon atoms to remain linked in stable structures. This makes the formation of long chains, branches and rings possible.

3 Marks 14. Explain why carbon forms a large number of compounds.

Carbon forms a large number of compounds because it has valency four, shows catenation and forms stable covalent bonds. It can also form single, double and triple bonds.

3 Marks 15. How does methane demonstrate tetravalency?

In CH₄, one carbon atom shares electrons with four hydrogen atoms. It therefore forms four C–H covalent bonds, demonstrating tetravalency.

4 Marks 16. Explain tetravalency and catenation with examples.

Tetravalency: Carbon forms four covalent bonds. Example: CH₄.

Catenation: Carbon atoms bond with one another to form chains and rings. Example: C—C—C—C.

4 Marks 17. Why is catenation especially strong in carbon?

Carbon atoms are small in size, so the nucleus strongly attracts shared electrons. This produces strong C–C bonds. Therefore carbon can form stable and long chains.

4 Marks 18. Explain the different types of carbon-carbon bonds.

Carbon can form:
1. Single bond — C—C, as in ethane.
2. Double bond — C=C, as in ethene.
3. Triple bond — C≡C, as in ethyne.

4 Marks 19. Explain the relationship between tetravalency and catenation.

Tetravalency allows carbon to form four bonds, while catenation allows carbon atoms to bond with one another. Together they permit the formation of complex chains, branches and rings.

4 Marks 20. Why does carbon form covalent compounds instead of C⁴⁺ or C⁴⁻ ions?

Removing four electrons requires a very large amount of energy, while gaining four electrons would produce an unstable ion. Therefore carbon achieves stability mainly by sharing electrons and forming covalent bonds.

5 Marks 21. Explain why carbon is considered a versatile element.

Carbon is versatile because:
1. It has valency four.
2. It shows strong catenation.
3. It forms strong C–C bonds.
4. It forms single, double and triple bonds.
5. It combines with many other elements.
Hence it forms a huge variety of compounds.

5 Marks 22. Explain the importance of tetravalency in carbon compounds.

Tetravalency allows one carbon atom to form four covalent bonds. Carbon can therefore combine with hydrogen, oxygen, nitrogen, sulphur, halogens and other carbon atoms. This produces diverse and complex molecular structures.

5 Marks 23. Explain the importance of catenation in carbon chemistry.

Catenation allows carbon atoms to bond with each other repeatedly. As a result, straight chains, branched chains and rings can be formed. This greatly increases the number and structural diversity of carbon compounds.

5 Marks 24. Differentiate between tetravalency and catenation.

Tetravalency	Catenation
Ability to form four covalent bonds.	Ability to bond with other carbon atoms.
Due to four valence electrons.	Supported by strong C–C bonds.
Example: CH₄.	Example: C—C—C—C.

5 Marks 25. Explain why carbon forms chains, branches and rings.

Carbon shows catenation because it forms strong C–C bonds. Since carbon is tetravalent, each carbon atom can form bonds in different directions. Therefore straight chains, branched chains and cyclic structures can be produced.

6 Marks 26. Explain in detail the versatile nature of carbon.

Carbon is highly versatile because:

1. It has four valence electrons and shows tetravalency.
2. It forms strong covalent bonds.
3. It shows excellent catenation.
4. It forms straight and branched chains.
5. It forms cyclic compounds.
6. It can form single, double and triple bonds.

These properties result in a huge variety of stable carbon compounds.

6 Marks 27. Explain tetravalency of carbon with the formation of methane.

Carbon has electronic configuration 2,4 and therefore has four valence electrons. It shares one electron with each of four hydrogen atoms. Each hydrogen shares one electron with carbon. Consequently, four C–H covalent bonds are formed.

CH₄ = Four C–H covalent bonds

Thus methane demonstrates the tetravalency of carbon.

6 Marks 28. Explain catenation and its role in the formation of carbon compounds.

Catenation is the ability of carbon to form bonds with other carbon atoms. Carbon forms strong C–C bonds because of its small atomic size. These bonds can continue repeatedly to produce long chains, branched structures and rings. Therefore catenation is one of the major reasons for the enormous variety of carbon compounds.

6 Marks 29. Why does carbon form a greater variety of compounds than most elements?

Carbon has four valence electrons and forms four covalent bonds. It shows strong catenation and can form stable C–C bonds. It can produce straight chains, branches and rings and can form single, double and triple bonds. It also combines with many elements. Therefore carbon forms an exceptionally large variety of compounds.

6 Marks 30. Explain the statement: “Tetravalency and catenation make carbon a versatile element.”

Tetravalency enables carbon to form four covalent bonds with the same or different atoms. Catenation enables carbon to bond with other carbon atoms. Because of these two properties, carbon can form long chains, branched chains and rings. It can also form single, double and triple bonds. Hence carbon produces a very large number of stable compounds and is called a versatile element.

15. Foundation + Competitive Quick Revision

🔥 Super Important Facts:

• Carbon atomic number = 6
• Electronic configuration = 2,4
• Valence electrons = 4
• Valency = 4
• Tetravalency = four covalent bonds.
• Catenation = carbon-carbon bonding.
• Carbon forms straight, branched and cyclic structures.
• Carbon forms C—C, C=C and C≡C bonds.
• Small atomic size of carbon helps form strong C–C bonds.
• Carbon shows greater catenation than silicon.
• CH₄ demonstrates tetravalency.
• C—C—C—C demonstrates catenation.

16. One-Line Revision | एक पंक्ति में पुनरावृत्ति

Carbon's Versatility = Tetravalency + Catenation + Strong C–C Bonds + Multiple Bond Formation.

हिन्दी:
कार्बन की बहुमुखी प्रकृति = चतुसंयोजकता + शृंखलन + मजबूत C–C बंध + विभिन्न प्रकार के बंध बनाने की क्षमता।

Class 10th Science Chapter 4 – Carbon and Its Compounds | Introduction, Occurrence and Importance of Carbon

🧪 Carbon and Its Compounds

Introduction, Occurrence and Importance of Carbon

Class 10 Science | CBSE + Foundation + Competitive Level

🧬 Carbon — Introduction, Occurrence & Importance

1. Introduction to Carbon | कार्बन का परिचय

English:
Carbon is one of the most important elements found in nature. It is a non-metal with atomic number 6 and symbol C. Carbon is present in living organisms as well as in many non-living substances. It forms a very large number of compounds because of its special properties such as tetravalency and catenation.

हिन्दी:
कार्बन प्रकृति में पाए जाने वाले सबसे महत्वपूर्ण तत्वों में से एक है। यह एक अधातु है जिसका परमाणु क्रमांक 6 तथा प्रतीक C है। कार्बन जीवित प्राणियों तथा अनेक निर्जीव पदार्थों में पाया जाता है। इसकी चतुसंयोजकता (Tetravalency) तथा शृंखलन (Catenation) जैसी विशेषताओं के कारण यह बहुत बड़ी संख्या में यौगिक बनाता है।

2. Position of Carbon in the Periodic Table | आवर्त सारणी में कार्बन की स्थिति

Property / गुण	Carbon / कार्बन
Symbol / प्रतीक	C
Atomic Number / परमाणु क्रमांक	6
Electronic Configuration / इलेक्ट्रॉनिक विन्यास	2, 4
Valence Electrons / संयोजकता इलेक्ट्रॉन	4
Group / समूह	14
Period / आवर्त	2
Nature / प्रकृति	Non-metal / अधातु

3. Electronic Configuration of Carbon | कार्बन का इलेक्ट्रॉनिक विन्यास

Carbon has atomic number 6. Therefore, a neutral carbon atom has six electrons.

Electronic configuration:

K-shell = 2     L-shell = 4

Thus:

Carbon = 2, 4

Carbon has four electrons in its outermost shell. It therefore tends to form four covalent bonds to achieve a stable electronic configuration.

हिन्दी:
कार्बन का परमाणु क्रमांक 6 है। इसलिए उदासीन कार्बन परमाणु में 6 इलेक्ट्रॉन होते हैं। इसका इलेक्ट्रॉनिक विन्यास:

2, 4

बाह्यतम कोश में 4 इलेक्ट्रॉन होने के कारण कार्बन सामान्यतः चार सहसंयोजक बंध बनाता है।

4. Occurrence of Carbon | कार्बन की उपस्थिति

Carbon occurs in both free state and combined state.

1. Free State | मुक्त अवस्था Carbon occurs in different forms such as:

• Diamond — हीरा
• Graphite — ग्रेफाइट
• Fullerenes — फुलरीन

These are different allotropes of carbon.
2. Combined State | संयुक्त अवस्था Carbon is found in:

• Carbon dioxide (CO₂) in air
• Carbonates such as calcium carbonate
• Hydrocarbons such as methane
• Coal and petroleum
• Organic compounds present in living organisms

हिन्दी:
कार्बन मुक्त तथा संयुक्त दोनों अवस्थाओं में पाया जाता है। मुक्त अवस्था में हीरा, ग्रेफाइट तथा फुलरीन इसके प्रमुख रूप हैं। संयुक्त अवस्था में यह वायु के CO₂, कार्बोनेट, कोयला, पेट्रोलियम, प्राकृतिक गैस तथा जीवित जीवों के कार्बनिक यौगिकों में पाया जाता है।

5. Carbon in Living Organisms | जीवित प्राणियों में कार्बन

Carbon is a fundamental element of life. It is present in major biological molecules such as:

• Carbohydrates
• Proteins
• Fats
• DNA and RNA
• Vitamins

Almost all biological molecules contain carbon atoms.

हिन्दी:
कार्बन जीवन के लिए अत्यंत महत्वपूर्ण तत्व है। यह कार्बोहाइड्रेट, प्रोटीन, वसा, DNA, RNA तथा विटामिन जैसे प्रमुख जैविक अणुओं में पाया जाता है।

6. Carbon in the Atmosphere | वायुमंडल में कार्बन

The atmosphere contains carbon mainly in the form of carbon dioxide (CO₂). Plants use carbon dioxide during photosynthesis to prepare food.

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

हिन्दी:
वायुमंडल में कार्बन मुख्यतः कार्बन डाइऑक्साइड (CO₂) के रूप में पाया जाता है। हरे पौधे प्रकाश संश्लेषण के दौरान CO₂ का उपयोग करके भोजन बनाते हैं।

7. Carbon in Earth's Crust | पृथ्वी की भूपर्पटी में कार्बन

Carbon occurs in the Earth's crust mainly in the form of:

• Carbonates
• Coal
• Petroleum
• Natural gas
• Minerals containing carbon

For example, limestone mainly contains calcium carbonate.

CaCO₃ → Calcium Carbonate

हिन्दी:
पृथ्वी की भूपर्पटी में कार्बन मुख्यतः कार्बोनेट, कोयला, पेट्रोलियम तथा प्राकृतिक गैस के रूप में पाया जाता है। चूना पत्थर का प्रमुख घटक कैल्शियम कार्बोनेट है।

8. Importance of Carbon | कार्बन का महत्व

Carbon is important because:

1. It is the basic element of organic compounds.
2. It is essential for life.
3. It forms carbohydrates, proteins and fats.
4. It is present in fuels such as coal, petroleum and natural gas.
5. It is used in many industrial products.
6. Carbon compounds are used as medicines, polymers, dyes and detergents.
7. Diamond is used for cutting and polishing.
8. Graphite is used in electrodes and pencils.

हिन्दी: कार्बन का महत्व:

1. यह कार्बनिक यौगिकों का आधार है।
2. जीवन के लिए आवश्यक है।
3. कार्बोहाइड्रेट, प्रोटीन और वसा में पाया जाता है।
4. कोयला, पेट्रोलियम तथा प्राकृतिक गैस जैसे ईंधनों में पाया जाता है।
5. औद्योगिक उत्पादों में उपयोग होता है।
6. दवाइयों, पॉलिमर, रंगों तथा डिटर्जेंट में कार्बन यौगिक उपयोगी हैं।
7. हीरे का उपयोग काटने और पॉलिश करने में होता है।
8. ग्रेफाइट का उपयोग इलेक्ट्रोड तथा पेंसिल में होता है।

9. Why is Carbon So Important? | कार्बन इतना महत्वपूर्ण क्यों है?

Carbon is special mainly because of two properties:

① Tetravalency | चतुसंयोजकता

Carbon has four valence electrons and can form four covalent bonds.

② Catenation | शृंखलन

Carbon atoms can bond with one another to form long chains, branched chains and rings.

C — C — C — C — C

Because of these properties, carbon forms an enormous number of compounds.

10. Carbon and Fuels | कार्बन और ईंधन

Many important fuels contain carbon. Examples:

• Coal
• Petrol
• Diesel
• CNG
• LPG
• Natural Gas

Most of these fuels contain hydrocarbons. Hydrocarbons are compounds made up of carbon and hydrogen.

हिन्दी:
अनेक महत्वपूर्ण ईंधनों में कार्बन पाया जाता है। जैसे कोयला, पेट्रोल, डीजल, CNG, LPG तथा प्राकृतिक गैस। कार्बन और हाइड्रोजन से बने यौगिकों को हाइड्रोकार्बन कहते हैं।

11. Important Forms of Carbon | कार्बन के महत्वपूर्ण रूप

Form / रूप	Important Property / प्रमुख गुण	Use / उपयोग
Diamond / हीरा	Very hard / अत्यंत कठोर	Cutting, jewellery / काटने, आभूषण
Graphite / ग्रेफाइट	Soft and conducts electricity / मुलायम एवं विद्युत का चालक	Pencils, electrodes / पेंसिल, इलेक्ट्रोड
Fullerene / फुलरीन	Molecular form of carbon / कार्बन का आणविक रूप	Research and nanotechnology / अनुसंधान एवं नैनोप्रौद्योगिकी

12. Quick Concept Summary | त्वरित पुनरावृत्ति

Remember:

• Carbon symbol = C
• Atomic number = 6
• Electronic configuration = 2,4
• Valence electrons = 4
• Group = 14
• Period = 2
• Carbon is a non-metal.
• Carbon shows tetravalency.
• Carbon shows catenation.
• Carbon is present in living organisms.
• CO₂ is an important carbon-containing compound in the atmosphere.
• Diamond and graphite are allotropes of carbon.

13. MCQs — 30 Questions | बहुविकल्पीय प्रश्न

1. What is the atomic number of carbon?
कार्बन का परमाणु क्रमांक क्या है?

A) 4

B) 6

C) 8

D) 12

Answer: B) 6

2. What is the symbol of carbon?
कार्बन का प्रतीक क्या है?

A) Ca

B) Co

C) C

D) Cr

Answer: C) C

3. The electronic configuration of carbon is:
कार्बन का इलेक्ट्रॉनिक विन्यास है:

A) 2,4

B) 2,6

C) 4,2

D) 2,8

Answer: A) 2,4

4. Carbon belongs to which group?
कार्बन किस समूह का तत्व है?

A) Group 1

B) Group 14

C) Group 17

D) Group 18

Answer: B) Group 14

5. Carbon is a:
कार्बन एक है:

A) Metal

B) Metalloid

C) Noble gas

D) Non-metal

Answer: D) Non-metal

6. How many valence electrons does carbon have?
कार्बन में कितने संयोजकता इलेक्ट्रॉन होते हैं?

A) 2

B) 3

C) 4

D) 6

Answer: C) 4

7. Which property allows carbon to form long chains?
कौन-सा गुण कार्बन को लंबी शृंखलाएँ बनाने में सक्षम बनाता है?

A) Catenation

B) Ionisation

C) Sublimation

D) Reduction

Answer: A) Catenation

8. Which is an allotrope of carbon?
निम्न में से कार्बन का अपररूप कौन-सा है?

A) Sodium

B) Diamond

C) Calcium

D) Sulphuric acid

Answer: B) Diamond

9. Which form of carbon conducts electricity?
कार्बन का कौन-सा रूप विद्युत का चालक है?

A) Diamond

B) Graphite

C) Fullerene only

D) Coal only

Answer: B) Graphite

10. Which form of carbon is extremely hard?
कार्बन का कौन-सा रूप अत्यंत कठोर है?

A) Graphite

B) Coal

C) Diamond

D) Coke

Answer: C) Diamond

11. Carbon dioxide is mainly present in:
कार्बन डाइऑक्साइड मुख्यतः कहाँ पाई जाती है?

A) Atmosphere

B) Pure metals

C) Table salt

D) Mercury

Answer: A) Atmosphere

12. Which process uses carbon dioxide?
कौन-सी प्रक्रिया कार्बन डाइऑक्साइड का उपयोग करती है?

A) Respiration

B) Photosynthesis

C) Rusting

D) Melting

Answer: B) Photosynthesis

13. Which molecule is produced during photosynthesis?

A) Glucose

B) Sodium chloride

C) Hydrochloric acid

D) Calcium oxide

Answer: A) Glucose

14. Carbon is an essential element of:

A) Only rocks

B) Living organisms

C) Only metals

D) Only water

Answer: B) Living organisms

15. Which of the following contains carbon?

A) Proteins

B) Carbohydrates

C) Fats

D) All of these

Answer: D) All of these

16. Carbon occurs in the Earth's crust in the form of:

A) Carbonates

B) Only oxygen

C) Only nitrogen

D) Only hydrogen

Answer: A) Carbonates

17. The main component of limestone is:

A) NaCl

B) CaCO₃

C) H₂O

D) CO

Answer: B) CaCO₃

18. Hydrocarbons contain:

A) Carbon and oxygen

B) Hydrogen and oxygen

C) Carbon and hydrogen

D) Carbon and nitrogen

Answer: C) Carbon and hydrogen

19. Which is a carbon-rich fuel?

A) Coal

B) Water

C) Oxygen

D) Sodium chloride

Answer: A) Coal

20. Carbon forms a large number of compounds mainly because of:

A) Tetravalency and catenation

B) High density only

C) Metallic nature

D) Radioactivity

Answer: A) Tetravalency and catenation

21. The valency of carbon is:

A) 1

B) 2

C) 4

D) 6

Answer: C) 4

22. Which is NOT an allotrope of carbon?

A) Diamond

B) Graphite

C) Fullerene

D) Calcium carbonate

Answer: D) Calcium carbonate

23. Which carbon allotrope is used in pencils?

A) Diamond

B) Graphite

C) Fullerene

D) Coal

Answer: B) Graphite

24. Carbon has how many electrons in its outermost shell?

A) 2

B) 4

C) 6

D) 8

Answer: B) 4

25. Which gas is an important carbon-containing atmospheric gas?

A) CO₂

B) O₂

C) N₂

D) H₂

Answer: A) CO₂

26. Which of the following is a biological molecule containing carbon?

A) Protein

B) Sodium metal

C) Copper

D) Silver

Answer: A) Protein

27. Carbon is located in which period?

A) Period 1

B) Period 2

C) Period 3

D) Period 4

Answer: B) Period 2

28. Which property means the ability of carbon to bond with itself?

A) Tetravalency

B) Catenation

C) Oxidation

D) Neutralisation

Answer: B) Catenation

29. Which substance is mainly calcium carbonate?

A) Limestone

B) Petrol

C) CNG

D) Graphite

Answer: A) Limestone

30. Carbon is important for life because it:

A) Forms many biological compounds

B) Is a noble gas

C) Cannot form bonds

D) Is highly radioactive

Answer: A) Forms many biological compounds

14. Subjective Questions — 30 Questions | वर्णनात्मक प्रश्न

1 Mark 1. What is carbon?

Carbon is a non-metallic element with atomic number 6 and symbol C.
हिन्दी: कार्बन परमाणु क्रमांक 6 वाला अधात्विक तत्व है।

1 Mark 2. Write the atomic number of carbon.

Atomic number = 6.

1 Mark 3. Write the electronic configuration of carbon.

Electronic configuration = 2,4.

1 Mark 4. Name two allotropes of carbon.

Diamond and graphite.

1 Mark 5. What is the valency of carbon?

The valency of carbon is 4.

2 Marks 6. Where is carbon found in nature?

Carbon is found in free and combined states. In free state it occurs as diamond, graphite and fullerene. In combined state it occurs in carbon dioxide, carbonates, coal, petroleum and organic compounds.

2 Marks 7. Why is carbon important for living organisms?

Carbon forms important biological molecules such as carbohydrates, proteins, fats, DNA and RNA. Therefore, it is essential for life.

2 Marks 8. What are allotropes of carbon?

Different structural forms of the same element having different physical properties are called allotropes. Diamond, graphite and fullerene are allotropes of carbon.

2 Marks 9. Write two uses of graphite.

1. It is used in pencils.
2. It is used for making electrodes because it conducts electricity.

2 Marks 10. Write two uses of diamond.

Diamond is used in jewellery and for cutting/glass-polishing because it is extremely hard.

3 Marks 11. Explain the occurrence of carbon.

Carbon occurs:
1. In free state as diamond, graphite and fullerene.
2. In atmosphere mainly as CO₂.
3. In Earth's crust as carbonates, coal, petroleum and natural gas.

3 Marks 12. Explain the electronic configuration of carbon.

Carbon has atomic number 6, so it has six electrons. Two electrons occupy the first shell and four electrons occupy the second shell.
Therefore, its electronic configuration is 2,4. It has four valence electrons.

3 Marks 13. What is catenation? Why is it important?

Catenation is the ability of carbon atoms to bond with one another. It allows carbon to form long chains, branched chains and rings, resulting in a huge variety of carbon compounds.

3 Marks 14. What is tetravalency of carbon?

Carbon has four electrons in its valence shell. It therefore forms four covalent bonds with other atoms to complete its octet. This property is called tetravalency.

3 Marks 15. Explain the importance of carbon in fuels.

Coal, petroleum, natural gas, LPG, CNG and many other fuels contain carbon compounds. On combustion they release energy, which is used for domestic, transport and industrial purposes.

4 Marks 16. Explain why carbon forms a very large number of compounds.

Carbon forms a very large number of compounds because:
1. It has valency four.
2. It forms strong covalent bonds.
3. It shows catenation.
4. It can form single, double and triple bonds.

4 Marks 17. Describe the importance of carbon in living organisms.

Carbon is the structural basis of organic molecules. It is present in carbohydrates, proteins, fats, nucleic acids and vitamins. These molecules perform structural, energy-related and genetic functions in living organisms.

4 Marks 18. Differentiate between diamond and graphite.

Diamond	Graphite
Very hard	Soft
Does not conduct electricity	Conducts electricity
Used in jewellery and cutting	Used in pencils and electrodes

4 Marks 19. Explain the occurrence of carbon in the atmosphere and Earth's crust.

In the atmosphere carbon occurs mainly as carbon dioxide. In Earth's crust it occurs in carbonates such as calcium carbonate and in fossil fuels such as coal, petroleum and natural gas.

4 Marks 20. Explain the role of carbon dioxide in photosynthesis.

Green plants absorb CO₂ from the atmosphere. In the presence of sunlight and chlorophyll, CO₂ reacts with water to produce glucose and oxygen.

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

5 Marks 21. Explain the important properties of carbon responsible for its versatility.

The major properties are:
1. Tetravalency — carbon forms four covalent bonds.
2. Catenation — carbon bonds with itself.
3. Strong C–C bonds.
4. Formation of single, double and triple bonds.
5. Ability to bond with elements such as H, O, N, S and halogens.

5 Marks 22. Describe different forms of carbon and their uses.

Diamond: Jewellery and cutting tools.
Graphite: Pencils and electrodes.
Fullerene: Scientific research and nanotechnology.
These forms have different structures and therefore different properties.

5 Marks 23. Discuss the importance of carbon in daily life.

Carbon compounds are present in fuels, food, medicines, plastics, fibres, detergents, dyes, cosmetics and many industrial materials. Carbon-based fuels provide energy for transportation and industries.

5 Marks 24. Explain the occurrence of carbon in free and combined states.

In free state carbon occurs as diamond, graphite and fullerene. In combined state it occurs as CO₂, carbonates, hydrocarbons, coal, petroleum, natural gas and organic compounds in living organisms.

5 Marks 25. Why is carbon considered the backbone of life?

Carbon can form stable bonds with itself and with many other elements. It forms complex molecules such as carbohydrates, proteins, fats and nucleic acids. These compounds are essential for life processes.

6 Marks 26. Explain the position, electronic configuration and importance of carbon.

Carbon has atomic number 6 and belongs to Group 14 and Period 2. Its electronic configuration is 2,4, so it has four valence electrons.

Carbon is important because it forms a large number of compounds due to tetravalency and catenation. It is present in living organisms, fuels, minerals and many useful materials.

6 Marks 27. Explain the occurrence and importance of carbon in nature.

Carbon occurs in free forms such as diamond, graphite and fullerene. It occurs in combined forms as CO₂, carbonates, fossil fuels and organic compounds.

It is essential for living organisms and is also important in fuels, medicines, polymers, dyes and several industrial products.

6 Marks 28. Explain why carbon forms an enormous number of compounds.

Carbon has four valence electrons and forms four covalent bonds. It forms strong carbon-carbon bonds and shows catenation. It can form straight chains, branched chains and rings. It can also form single, double and triple bonds. Carbon can combine with H, O, N, S and halogens. Hence, millions of carbon compounds are possible.

6 Marks 29. Describe the importance of carbon in biological and industrial systems.

Biologically, carbon forms carbohydrates, proteins, fats, DNA and RNA. Industrially, carbon compounds are used in fuels, plastics, synthetic fibres, medicines, dyes, detergents and solvents. Thus carbon is important in both life and industry.

6 Marks 30. Write a detailed note on Carbon — Introduction, Occurrence and Importance.

Introduction:
Carbon is a non-metal with atomic number 6 and symbol C. Its electronic configuration is 2,4.

Occurrence:
Carbon occurs in free forms such as diamond, graphite and fullerene. It occurs in combined forms in CO₂, carbonates, coal, petroleum, natural gas and organic compounds.

Importance:
Carbon is the basic element of organic compounds and is essential for life. It forms carbohydrates, proteins, fats and nucleic acids. Carbon compounds are also important in fuels, medicines, polymers and several industrial products.

Special Properties:
Its tetravalency and catenation enable it to form a huge variety of compounds.

15. Competitive Level — Key Points | प्रतियोगी परीक्षा के महत्वपूर्ण तथ्य

🔥 High-Yield Facts:

• Atomic number of Carbon = 6
• Mass number of most common carbon isotope = 12
• Electronic configuration = 2,4
• Group = 14
• Period = 2
• Valency = 4
• Symbol = C
• Carbon is a non-metal.
• Diamond and graphite are allotropes of carbon.
• Graphite conducts electricity.
• Diamond is one of the hardest naturally occurring substances.
• Carbon dioxide is used by green plants during photosynthesis.
• Catenation = self-linking property of carbon.
• Tetravalency = ability of carbon to form four covalent bonds.
• Hydrocarbons contain carbon and hydrogen.

16. One-Line Revision | एक पंक्ति में पुनरावृत्ति

Carbon = C = Atomic Number 6 = Configuration 2,4 = Group 14 = Period 2 = Valency 4 = Tetravalent + Catenation = Huge Number of Compounds.

हिन्दी:
कार्बन = C = परमाणु क्रमांक 6 = विन्यास 2,4 = समूह 14 = आवर्त 2 = संयोजकता 4 = चतुसंयोजकता + शृंखलन = असंख्य यौगिक।

Carbon – Introduction | Class 10 Science

🧪 Carbon — Introduction

Class 10 Science | Carbon and Its Compounds | CBSE + Foundation + Competitive

🧪 Carbon — Introduction / कार्बन का परिचय

📘 1. Introduction to Carbon / कार्बन का परिचय

English: Carbon is a non-metallic element with atomic number 6. It is represented by the symbol C. Carbon is present in living organisms, fuels, food, medicines, plastics and many other substances.

हिन्दी: कार्बन एक अधातु तत्व है जिसका परमाणु क्रमांक 6 है। इसका प्रतीक C है। कार्बन जीवित जीवों, ईंधनों, भोजन, औषधियों, प्लास्टिक तथा अनेक अन्य पदार्थों में पाया जाता है।

Atomic Number of Carbon = 6
Electronic Configuration = 2, 4
Valency = 4

🌐 2. Why Does Carbon Form a Large Number of Compounds?

Carbon forms a very large number of compounds mainly because of two important properties:

1. Catenation / श्रृंखलन
Carbon atoms can bond with one another to form long chains, branched chains and rings.

2. Tetravalency / चतुसंयोजकता
Carbon has four valence electrons and can form four covalent bonds with other atoms.

Key Concept:

Catenation + Tetravalency → Enormous number of carbon compounds

श्रृंखलन + चतुसंयोजकता → कार्बन यौगिकों की बहुत बड़ी संख्या

🔗 3. What is Catenation? / श्रृंखलन क्या है?

Catenation is the ability of an element to form covalent bonds with atoms of the same element, thereby forming chains, branches and rings.

श्रृंखलन किसी तत्व के परमाणुओं की अपने ही समान तत्व के परमाणुओं के साथ सहसंयोजक बंध बनाने की क्षमता है, जिससे श्रृंखला, शाखित श्रृंखला और वलय बन सकते हैं।

C — C — C — C — C
Straight carbon chain / सीधी कार्बन श्रृंखला

   C
   |
C — C — C
   |
   C
Branched carbon structure / शाखित संरचना

Carbon shows extensive catenation because the C–C bond is strong and stable.

कार्बन में व्यापक श्रृंखलन का प्रमुख कारण यह है कि C–C बंध मजबूत और स्थिर होता है।

4️⃣ 4. What is Tetravalency of Carbon? / कार्बन की चतुसंयोजकता क्या है?

Carbon has atomic number 6 and electronic configuration 2,4. Therefore, it has four electrons in its outermost shell.

कार्बन का परमाणु क्रमांक 6 और इलेक्ट्रॉनिक विन्यास 2,4 है। इसलिए इसकी बाहरी कक्षा में चार इलेक्ट्रॉन होते हैं।

Carbon generally forms four covalent bonds to achieve a stable electronic configuration.

स्थिर इलेक्ट्रॉनिक विन्यास प्राप्त करने के लिए कार्बन सामान्यतः चार सहसंयोजक बंध बनाता है।

    H
    |
H — C — H
    |
    H
Methane (CH₄) / मीथेन

Exam Point:
The valency of carbon is 4, so carbon is called a tetravalent element.

परीक्षा बिंदु:
कार्बन की संयोजकता 4 होती है, इसलिए इसे चतुसंयोजी तत्व कहते हैं।

🤝 5. Why Does Carbon Form Covalent Bonds?

Carbon has four valence electrons. It would require four more electrons to complete its outer shell, but losing or gaining four electrons is energetically difficult.

कार्बन की बाहरी कक्षा में चार इलेक्ट्रॉन होते हैं। बाहरी कक्षा को पूर्ण करने के लिए इसे चार और इलेक्ट्रॉनों की आवश्यकता होती है, लेकिन चार इलेक्ट्रॉन खोना या प्राप्त करना ऊर्जात्मक रूप से कठिन होता है।

Therefore, carbon generally achieves stability by sharing electrons with other atoms.

इसलिए कार्बन सामान्यतः अन्य परमाणुओं के साथ इलेक्ट्रॉनों की साझेदारी करके स्थिरता प्राप्त करता है।

The shared electrons form covalent bonds.

इलेक्ट्रॉनों की यह साझेदारी सहसंयोजक बंध बनाती है।

🧬 6. Covalent Bond Formation in Methane / मीथेन में सहसंयोजक बंध

Methane has the formula CH₄. One carbon atom shares electrons with four hydrogen atoms.

मीथेन का सूत्र CH₄ है। इसमें एक कार्बन परमाणु चार हाइड्रोजन परमाणुओं के साथ इलेक्ट्रॉनों की साझेदारी करता है।

CH₄ = Carbon + 4 Hydrogen atoms

Each C–H bond is formed by sharing one pair of electrons between carbon and hydrogen.

प्रत्येक C–H बंध कार्बन और हाइड्रोजन के बीच इलेक्ट्रॉनों की एक जोड़ी की साझेदारी से बनता है।

⚛️ 7. Electron Sharing in Carbon / कार्बन में इलेक्ट्रॉन साझेदारी

Concept / अवधारणा	Explanation / व्याख्या
Valence electrons	Carbon has 4 valence electrons.
Required for octet	Carbon needs 4 more electrons to complete its octet.
Loss of electrons	Loss of four electrons requires very high energy.
Gain of electrons	Gain of four electrons is also energetically unfavourable.
Solution	Carbon shares electrons and forms covalent bonds.

🔬 8. General Features of Carbon Covalent Compounds

• They generally have strong covalent bonds within molecules.
• They generally have relatively low melting and boiling points compared with ionic compounds.
• They are generally poor conductors of electricity because they do not have free ions.
• Many carbon compounds are molecular in nature.

🔗 9. Types of Covalent Bonds in Carbon Compounds

Bond	Shared Electron Pairs	Example
Single bond	1 pair	Ethane (C₂H₆)
Double bond	2 pairs	Ethene (C₂H₄)
Triple bond	3 pairs	Ethyne (C₂H₂)

🔗 10. Strength of Carbon–Carbon Bond / कार्बन-कार्बन बंध

The carbon atom is relatively small, so the nucleus of one carbon atom can form a strong covalent bond with another carbon atom.

कार्बन परमाणु का आकार अपेक्षाकृत छोटा होता है, इसलिए एक कार्बन परमाणु का नाभिक दूसरे कार्बन परमाणु के साथ मजबूत सहसंयोजक बंध बना सकता है।

This strong C–C bonding is an important reason for extensive catenation.

यह मजबूत C–C बंध व्यापक श्रृंखलन का एक महत्वपूर्ण कारण है।

📊 11. Catenation vs Tetravalency

Catenation / श्रृंखलन	Tetravalency / चतुसंयोजकता
Ability to bond with other carbon atoms.	Ability to form four covalent bonds.
Produces chains, branches and rings.	Allows carbon to bond with H, O, N, halogens and other atoms.
Responsible for carbon skeleton formation.	Responsible for many possible bonding arrangements.

🌐 12. Why Carbon Compounds Are So Numerous

The huge variety of carbon compounds arises because carbon can:

1. Bond with other carbon atoms.
2. Form long chains.
3. Form branched chains.
4. Form cyclic structures.
5. Form single, double and triple bonds.
6. Bond with hydrogen, oxygen, nitrogen, sulphur and halogens.

📝 13. 30 MCQs – Carbon Introduction

Q1 What is the atomic number of carbon? / कार्बन का परमाणु क्रमांक क्या है?

A. 4

B. 6

C. 8

D. 12

Answer: B — Carbon has atomic number 6.

Q2 What is the electronic configuration of carbon?

A. 2,4

B. 2,6

C. 4,2

D. 2,8

Answer: A — Carbon has 6 electrons: 2 in K-shell and 4 in L-shell.

Q3 What is the valency of carbon?

A. 1

B. 2

C. 3

D. 4

Answer: D — Carbon is tetravalent.

Q4 What is catenation?

A. Bonding of carbon with metals only

B. Bonding of atoms of the same element to form chains or rings

C. Loss of all electrons

D. Formation of ions only

Answer: B.

Q5 Why does carbon form a large number of compounds?

A. Due to catenation and tetravalency

B. Due to radioactivity

C. Due to metallic nature

D. Due to its high density

Answer: A.

Q6 Carbon generally forms which type of bonds?

A. Ionic bonds only

B. Covalent bonds

C. Metallic bonds only

D. Hydrogen bonds only

Answer: B.

Q7 How many valence electrons does carbon have?

A. 2

B. 3

C. 4

D. 6

Answer: C.

Q8 Carbon forms covalent bonds mainly by:

A. Sharing electrons

B. Losing all protons

C. Gaining neutrons

D. Losing its nucleus

Answer: A.

Q9 Which molecule demonstrates tetravalency of carbon?

A. H₂

B. CH₄

C. O₂

D. N₂

Answer: B — Methane demonstrates four C–H bonds.

Q10 The ability of carbon to form bonds with itself is called:

A. Ionisation

B. Catenation

C. Reduction

D. Oxidation

Answer: B.

Q11 Carbon can form:

A. Only straight chains

B. Only rings

C. Chains, branches and rings

D. Only ionic lattices

Answer: C.

Q12 Which bond is formed by sharing one pair of electrons?

A. Single covalent bond

B. Double covalent bond

C. Triple covalent bond

D. Ionic bond

Answer: A.

Q13 A double covalent bond involves sharing of:

A. One electron

B. One pair of electrons

C. Two pairs of electrons

D. Four pairs of electrons

Answer: C.

Q14 A triple bond involves sharing of:

A. One pair

B. Two pairs

C. Three pairs

D. Four pairs

Answer: C.

Q15 Which is an example of a molecule containing a double bond between carbon atoms?

A. Ethane

B. Ethene

C. Methane

D. Propane

Answer: B — Ethene contains C=C.

Q16 Which compound contains a carbon-carbon triple bond?

A. Ethane

B. Ethene

C. Ethyne

D. Methane

Answer: C — Ethyne contains C≡C.

Q17 Why is C–C bonding important in carbon chemistry?

A. It enables formation of carbon chains

B. It prevents all compounds

C. It makes carbon radioactive

D. It removes valence electrons

Answer: A.

Q18 Carbon has how many electrons in its outermost shell?

A. 1

B. 2

C. 4

D. 8

Answer: C.

Q19 Why does carbon not normally form C⁴⁺ easily?

A. Removing four electrons requires very high energy

B. Carbon has no electrons

C. Carbon is a noble gas

D. Carbon has eight valence electrons

Answer: A.

Q20 Why does carbon not normally form C⁴⁻ easily?

A. Gaining four electrons is energetically unfavourable

B. Carbon has no nucleus

C. Carbon is a metal

D. Carbon has zero valency

Answer: A.

Q21 The stable bonding strategy of carbon is mainly:

A. Electron sharing

B. Complete electron loss

C. Complete electron gain

D. Proton sharing

Answer: A.

Q22 Which of the following is NOT a major reason for the huge number of carbon compounds?

A. Catenation

B. Tetravalency

C. Ability to form multiple bonds

D. Very high atomic mass

Answer: D.

Q23 Carbon can form covalent bonds with:

A. Hydrogen

B. Oxygen

C. Nitrogen

D. All of these

Answer: D.

Q24 Which property allows carbon to form branched chains?

A. Catenation

B. Magnetism

C. Radioactivity

D. Metallic lustre

Answer: A.

Q25 Which statement about carbon is correct?

A. It has four valence electrons

B. It has one valence electron

C. It is a noble gas

D. It normally forms only ionic compounds

Answer: A.

Q26 Which is an important consequence of tetravalency?

A. Carbon can form many different structures

B. Carbon cannot bond with hydrogen

C. Carbon forms only salts

D. Carbon has no chemical activity

Answer: A.

Q27 Which of the following contains a carbon-carbon single bond?

A. Ethane

B. Ethene

C. Ethyne

D. Carbon dioxide

Answer: A.

Q28 The term tetravalency means carbon can generally form:

A. One covalent bond

B. Two covalent bonds

C. Three covalent bonds

D. Four covalent bonds

Answer: D.

Q29 Which feature is responsible for the stability of carbon chains?

A. Strong C–C bonds

B. Weak C–C bonds

C. Metallic bonding

D. Ionic bonding only

Answer: A.

Q30 Carbon chemistry is exceptionally diverse because carbon can:

A. Only form C–C single bonds

B. Form chains, branches, rings and multiple bonds

C. Only form ionic compounds

D. Only form compounds with oxygen

Answer: B.

✍️ 14. 30 Subjective Questions with Answers

1 Mark Q1. What is the atomic number of carbon?

Answer: 6.
हिन्दी: कार्बन का परमाणु क्रमांक 6 है।

1 Mark Q2. What is the valency of carbon?

Answer: 4.

1 Mark Q3. What is catenation?

Answer: The ability of carbon atoms to form covalent bonds with other carbon atoms is called catenation.

1 Mark Q4. How many valence electrons does carbon have?

Answer: Four.

1 Mark Q5. Name the type of bond generally formed by carbon.

Answer: Covalent bond.

2 Marks Q6. Why does carbon form a large number of compounds?

Answer: Carbon forms a large number of compounds mainly because of its catenation and tetravalency.

2 Marks Q7. What is tetravalency of carbon?

Answer: Carbon has four valence electrons and generally forms four covalent bonds. This property is called tetravalency.

2 Marks Q8. Why does carbon form covalent bonds?

Answer: Carbon has four valence electrons. Losing or gaining four electrons is energetically difficult, so carbon achieves stability mainly by sharing electrons and forming covalent bonds.

2 Marks Q9. Why is catenation important in carbon chemistry?

Answer: Catenation allows carbon atoms to form long chains, branched chains and rings, producing a very large variety of compounds.

2 Marks Q10. Write the electronic configuration of carbon.

Answer: Carbon has atomic number 6, so its electronic configuration is 2,4.

3 Marks Q11. Explain catenation with an example.

Answer: Catenation is the ability of carbon to form covalent bonds with other carbon atoms. It allows formation of chains, branches and rings. For example:

C–C–C–C

represents a carbon chain.

3 Marks Q12. Explain tetravalency of carbon.

Answer: Carbon has four electrons in its outermost shell. It shares electrons with other atoms and can generally form four covalent bonds. Therefore, carbon is called tetravalent.

3 Marks Q13. Why can carbon not easily form C⁴⁺ or C⁴⁻ ions?

Answer: Removing four electrons from carbon requires very high energy, while gaining four electrons is also energetically unfavourable. Hence carbon generally shares electrons instead of forming C⁴⁺ or C⁴⁻ ions.

3 Marks Q14. Explain why carbon forms covalent bonds.

Answer: Carbon has four valence electrons. It needs four more electrons for an octet, but complete transfer of four electrons is difficult. Therefore, it shares electrons with other atoms and forms covalent bonds.

3 Marks Q15. State three reasons for the large number of carbon compounds.

Answer:
1. Catenation.
2. Tetravalency.
3. Ability to form single, double and triple bonds.

4 Marks Q16. Explain the role of catenation in the formation of carbon compounds.

Answer: Carbon atoms form strong C–C covalent bonds. As a result, they can link with one another to form long chains, branched chains and rings. This enormous structural variety contributes greatly to the large number of carbon compounds.

4 Marks Q17. Explain the role of tetravalency in carbon chemistry.

Answer: Carbon can form four covalent bonds. These bonds can be formed with carbon as well as hydrogen, oxygen, nitrogen, sulphur and halogens. This allows many different molecular structures and compounds to exist.

4 Marks Q18. Differentiate between catenation and tetravalency.

Catenation	Tetravalency
Ability to bond with atoms of the same element.	Ability to form four covalent bonds.
Helps form chains, branches and rings.	Allows bonding with many different atoms.
Produces carbon skeletons.	Produces different bonding arrangements.

4 Marks Q19. Explain the formation of methane using covalent bonding.

Answer: Carbon has four valence electrons and each hydrogen has one valence electron. Carbon shares one electron with each of four hydrogen atoms. Thus, four C–H covalent bonds are formed and carbon achieves an octet.

Formula: CH₄

4 Marks Q20. Explain why carbon-carbon bonds are important.

Answer: C–C bonds are strong and stable. They allow carbon atoms to join together into long chains, branched structures and rings. This property is responsible for the enormous diversity of carbon compounds.

5 Marks Q21. Why does carbon form a large number of compounds? Explain in detail.

Answer:
Carbon forms a very large number of compounds because:
1. It shows extensive catenation.
2. It is tetravalent.
3. It forms strong C–C bonds.
4. It can form single, double and triple bonds.
5. It can combine with many elements such as H, O, N, S and halogens.

5 Marks Q22. Explain catenation and its importance.

Answer: Catenation is the ability of carbon atoms to form covalent bonds with one another. Because C–C bonds are strong, carbon can form long straight chains, branched chains and cyclic structures. Catenation is one of the main reasons for the large variety of carbon compounds.

5 Marks Q23. Explain tetravalency of carbon with reference to its electronic configuration.

Answer: Carbon has atomic number 6 and electronic configuration 2,4. It therefore has four valence electrons. Instead of completely losing or gaining four electrons, carbon generally shares electrons with other atoms. It can form four covalent bonds and is therefore called tetravalent.

5 Marks Q24. Why does carbon form covalent compounds instead of ionic compounds in most cases?

Answer: Carbon has four valence electrons. Losing four electrons requires very high energy, while gaining four electrons is also not favourable. Hence carbon achieves stability by sharing electrons with other atoms, resulting in covalent compounds.

5 Marks Q25. Explain how carbon can form different types of bonds.

Answer: Carbon can share one, two or three pairs of electrons between atoms. Thus it can form:

1. Single bond → one shared pair.
2. Double bond → two shared pairs.
3. Triple bond → three shared pairs.

Examples are ethane, ethene and ethyne respectively.

6 Marks Q26. Explain the four important reasons for the versatility of carbon.

Answer:
1. Tetravalency: Carbon can form four covalent bonds.

2. Catenation: Carbon atoms form strong C–C bonds.

3. Multiple bonding: Carbon can form single, double and triple bonds.

4. Combination with many elements: Carbon bonds with H, O, N, S and halogens, producing many different compounds.

6 Marks Q27. Explain why carbon does not normally form C⁴⁺ and C⁴⁻ ions.

Answer:
Carbon has four valence electrons.

Formation of C⁴⁺: Carbon would have to lose four electrons. This requires an extremely large amount of energy.

Formation of C⁴⁻: Carbon would have to gain four electrons. This is also energetically unfavourable because of electron-electron repulsion and the difficulty of accommodating four additional electrons.

Therefore, carbon generally shares electrons and forms covalent bonds.

6 Marks Q28. Describe the electronic basis of covalent bonding in carbon.

Answer:
Carbon has atomic number 6 and electronic configuration 2,4. It has four valence electrons and requires four more electrons to complete its octet. Complete transfer of four electrons is not energetically favourable. Therefore carbon shares electrons with other atoms. Shared electron pairs form covalent bonds, allowing carbon to achieve a stable outer-shell configuration.

6 Marks Q29. Explain how catenation and tetravalency together make carbon chemistry highly diverse.

Answer:
Catenation allows carbon atoms to join with one another and form long chains, branched chains and rings. Tetravalency allows each carbon atom to form four covalent bonds with carbon and other elements. Together, these properties permit a huge variety of molecular structures. Carbon can also form single, double and triple bonds, further increasing the diversity.

6 Marks Q30. “Carbon is a versatile element.” Justify the statement.

Answer:
Carbon is called versatile because:
1. It has tetravalency.
2. It shows extensive catenation.
3. It forms strong C–C bonds.
4. It forms straight and branched chains.
5. It forms cyclic structures.
6. It forms single, double and triple covalent bonds.
7. It combines with many elements to produce an enormous variety of compounds.

🚀 15. Quick Revision / त्वरित पुनरावृत्ति

Carbon Symbol → C

Atomic Number → 6

Electronic Configuration → 2,4

Valence Electrons → 4

Valency → 4

Catenation → Carbon atoms bond with one another to form chains, branches and rings.

Tetravalency → Carbon can form four covalent bonds.

Covalent Bond → Bond formed by sharing of electrons.

Single Bond → 1 shared electron pair

Double Bond → 2 shared electron pairs

Triple Bond → 3 shared electron pairs

🎯 CBSE Exam Tip:

सबसे महत्वपूर्ण चार बातें याद रखें:

1. Carbon has 4 valence electrons.
2. Carbon is tetravalent.
3. Carbon shows catenation.
4. Carbon mainly forms covalent bonds by sharing electrons.

Key Formula:
Catenation + Tetravalency + Multiple Bonding = Huge Diversity of Carbon Compounds