In the modern periodic table, the period indicates the value of: (n, l, m, or s)?

Modern Periodic Table & Quantum Numbers – Competitive Level

आधुनिक आवर्त सारणी एवं क्वांटम संख्याएँ – प्रतियोगी परीक्षा स्तर

1. In the modern periodic table, the period number of an element is generally related to which quantum number?
आधुनिक आवर्त सारणी में किसी element की period number सामान्यतः किस quantum number से संबंधित होती है?

1. Azimuthal quantum number (l)
2. Principal quantum number (n)
3. Magnetic quantum number (m_l)
4. Spin quantum number (m_s)

Answer / उत्तर: (B) Principal quantum number (n)

Solution / समाधान:
The highest principal quantum number present in the ground-state electronic configuration determines the period. अर्थात ground-state electronic configuration में उपस्थित highest principal quantum number n period को निर्धारित करता है।

2. If the last electron of an element enters the 4p subshell, the element belongs to which period?
यदि किसी element का अंतिम electron 4p subshell में प्रवेश करता है, तो वह किस period में होगा?

1. 2nd
2. 3rd
3. 4th
4. 5th

Answer / उत्तर: (C) 4th Period / चौथा Period

Solution / समाधान:
The principal quantum number of the outer shell is n = 4. Therefore, the element belongs to the 4th period. यहाँ outer shell का highest n = 4 है, इसलिए element 4th period में होगा।

3. An element has the electronic configuration [Ne] 3s²3p³. Its group and period are:
किसी element का electronic configuration [Ne] 3s²3p³ है। इसका group और period क्या होगा?

1. Group 13, Period 3
2. Group 15, Period 3
3. Group 15, Period 2
4. Group 16, Period 3

Answer / उत्तर: (B) Group 15, Period 3

Solution / समाधान:
Highest n = 3 → Period 3.
Valence electrons = 3s²3p³ = 5 → Group 15.

4. Which set of quantum numbers is possible for an electron in a 3d orbital?
3d orbital में electron के लिए निम्न में से कौन-सा quantum number set possible है?

1. n = 3, l = 2, m_l = +1, m_s = +1/2
2. n = 3, l = 3, m_l = 0, m_s = +1/2
3. n = 2, l = 2, m_l = 0, m_s = −1/2
4. n = 3, l = 2, m_l = +3, m_s = +1/2

Answer / उत्तर: (A)

Solution / समाधान:
For 3d: n = 3 and l = 2. For l = 2, m_l can be −2, −1, 0, +1, +2 and m_s = ±1/2. इसलिए option (A) सभी rules satisfy करता है।

5. The maximum number of electrons that can have n = 4 is:
n = 4 वाले shell में maximum कितने electrons हो सकते हैं?

1. 8
2. 16
3. 18
4. 32

Answer / उत्तर: (D) 32

Solution / समाधान:
Maximum electrons = 2n² = 2(4)² = 32.

6. For an electron in a 4f orbital, the values of n and l are:
4f orbital के electron के लिए n और l के values क्या होंगे?

1. n = 4, l = 0
2. n = 4, l = 1
3. n = 4, l = 2
4. n = 4, l = 3

Answer / उत्तर: (D) n = 4, l = 3

Solution / समाधान:
For f-subshell, l = 3. The number before the letter gives n = 4. इसलिए 4f के लिए n = 4, l = 3।

7. How many orbitals are possible for l = 3?
l = 3 के लिए कितने orbitals possible हैं?

1. 3
2. 5
3. 7
4. 9

Answer / उत्तर: (C) 7

Solution / समाधान:
Number of orbitals = 2l + 1 = 2(3) + 1 = 7. इसलिए l = 3 corresponds to f-subshell.

8. The possible values of m_l for l = 2 are:
l = 2 के लिए m_l के possible values क्या हैं?

1. −1, 0, +1
2. −2, −1, 0, +1, +2
3. 0, +1, +2
4. −2, 0, +2

Answer / उत्तर: (B)

Solution / समाधान:
m_l ranges from −l to +l. For l = 2: −2, −1, 0, +1, +2.

9. Which quantum number is responsible for the orientation of an orbital in space?
Space में orbital की orientation किस quantum number पर depend करती है?

1. n
2. l
3. m_l
4. m_s

Answer / उत्तर: (C) Magnetic quantum number (m_l)

Solution / समाधान:
Magnetic quantum number m_l determines the orientation of an orbital in space. अर्थात m_l orbital की spatial orientation बताता है।

10. Which of the following subshells cannot exist?
निम्न में से कौन-सा subshell exist नहीं कर सकता?

1. 2s
2. 2p
3. 2d
4. 3d

Answer / उत्तर: (C) 2d

Solution / समाधान:
For n = 2, possible l values are 0 and 1 only. Therefore, d-subshell (l = 2) cannot exist for n = 2. इसलिए 2d subshell impossible है।

11. Which subshell has the maximum number of orbitals?
निम्न में से किस subshell में maximum number of orbitals होते हैं?

1. s
2. p
3. d
4. f

Answer / उत्तर: (D) f

Solution / समाधान:
s = 1 orbital, p = 3, d = 5, f = 7. Therefore, f-subshell has the maximum number.

12. The maximum number of electrons in the 4d subshell is:
4d subshell में maximum कितने electrons हो सकते हैं?

1. 2
2. 6
3. 10
4. 14

Answer / उत्तर: (C) 10

Solution / समाधान:
d-subshell contains 5 orbitals and each orbital can hold 2 electrons. Therefore, 5 × 2 = 10 electrons.

13. An element with valence shell configuration ns²np⁵ belongs to:
ns²np⁵ configuration वाला element किस group से belong करता है?

1. Group 15
2. Group 16
3. Group 17
4. Group 18

Answer / उत्तर: (C) Group 17

Solution / समाधान:
Valence electrons = 2 + 5 = 7. Elements with 7 valence electrons in the p-block belong to Group 17.

14. An element with valence configuration ns²np⁶ generally belongs to:
ns²np⁶ configuration वाला element सामान्यतः किस group में होता है?

1. Group 16
2. Group 17
3. Group 18
4. Group 1

Answer / उत्तर: (C) Group 18

Solution / समाधान:
The valence shell is completely filled with 8 electrons, characteristic of noble gases. इसलिए यह सामान्यतः Group 18 में होता है।

15. Which element has the electronic configuration [Ar] 3d⁵4s²?
[Ar] 3d⁵4s² electronic configuration किस element की है?

1. Cr
2. Mn
3. Fe
4. Co

Answer / उत्तर: (B) Mn

Solution / समाधान:
[Ar] = 18 electrons; 3d⁵4s² adds 7 electrons. Total = 25 → Atomic number 25 = Manganese (Mn).

16. The element with atomic number 119 is expected to belong to:
Atomic number 119 वाला element किस group में expected है?

1. Group 1
2. Group 2
3. Group 17
4. Group 18

Answer / उत्तर: (A) Group 1

Solution / समाधान:
Expected configuration of Z = 119 is [Og] 8s¹. One electron in the outermost s-subshell indicates Group 1.

17. Which of the following represents a valid set of quantum numbers?
निम्न में से कौन-सा quantum numbers का valid set है?

1. n = 3, l = 3, m_l = 0, m_s = +1/2
2. n = 3, l = 2, m_l = −2, m_s = +1/2
3. n = 2, l = 1, m_l = 2, m_s = −1/2
4. n = 1, l = 1, m_l = 0, m_s = +1/2

Answer / उत्तर: (B)

Solution / समाधान:
For n = 3, l can be 0, 1 or 2. For l = 2, m_l can range from −2 to +2. Hence option (B) is valid.

18. Which quantum number can have only two values?
कौन-सी quantum number केवल दो values ले सकती है?

1. n
2. l
3. m_l
4. m_s

Answer / उत्तर: (D) m_s

Solution / समाधान:
Spin quantum number has only two possible values: +1/2 and −1/2.

19. Which pair represents elements belonging to the same group?
निम्न में से कौन-सी pair same group के elements को दर्शाती है?

1. Na and K
2. Na and Mg
3. Cl and Ar
4. O and F

Answer / उत्तर: (A) Na and K

Solution / समाधान:
Na has configuration [Ne]3s¹ and K has [Ar]4s¹. Both have ns¹ configuration and belong to Group 1.

20. Which trend generally increases from left to right across a period?
Period में left to right जाने पर सामान्यतः कौन-सी property बढ़ती है?

1. Atomic radius
2. Metallic character
3. Ionization enthalpy
4. Number of shells

Answer / उत्तर: (C) Ionization enthalpy

Solution / समाधान:
Across a period, effective nuclear charge generally increases and atomic size decreases. Therefore, ionization enthalpy generally increases.

21. Atomic radius generally decreases from left to right because:
Left to right atomic radius सामान्यतः क्यों घटता है?

1. Number of shells decreases
2. Effective nuclear charge increases
3. Atomic mass decreases
4. Neutrons disappear

Answer / उत्तर: (B) Effective nuclear charge increases

Solution / समाधान:
Electrons are added to the same principal shell while nuclear charge increases. This increases effective nuclear attraction and reduces atomic radius.

22. Which element has the largest atomic radius among Na, Mg, Al and Si?
Na, Mg, Al और Si में सबसे बड़ा atomic radius किसका है?

1. Na
2. Mg
3. Al
4. Si

Answer / उत्तर: (A) Na

Solution / समाधान:
These elements belong to the same period. Atomic radius decreases from left to right. Therefore, Na has the largest radius.

23. Which species has the largest size among Na⁺, Mg²⁺, F⁻ and O²⁻?
Na⁺, Mg²⁺, F⁻ और O²⁻ में सबसे बड़ा size किसका है?

1. Na⁺
2. Mg²⁺
3. F⁻
4. O²⁻

Answer / उत्तर: (D) O²⁻

Solution / समाधान:
All four species are isoelectronic with 10 electrons. In an isoelectronic series, size decreases as nuclear charge increases. O has the lowest nuclear charge among them, so O²⁻ is largest.

24. Which is the correct order of size for iodine species?
I, I⁺ और I⁻ के size का correct order क्या है?

1. I⁺ < I < I⁻
2. I⁻ < I < I⁺
3. I < I⁺ < I⁻
4. I⁻ < I⁺ < I

Answer / उत्तर: (A) I⁺ < I < I⁻

Solution / समाधान:
Cation formation decreases size due to loss of electron, while anion formation increases size due to increased electron-electron repulsion. Hence, I⁺ < I < I⁻.

25. Which element has the highest first ionization enthalpy among Li, Be, B and C?
Li, Be, B और C में highest first ionization enthalpy किसकी है?

1. Li
2. Be
3. B
4. C

Answer / उत्तर: (D) C

Solution / समाधान:
Ionization enthalpy generally increases across the period. Although Be > B due to subshell stability, the value for C is higher than Be. इसलिए दिए गए elements में C highest है।

26. Which element has an exceptional electronic configuration due to half-filled d-subshell stability?
Half-filled d-subshell stability के कारण किस element की electronic configuration exceptional है?

1. Sc
2. Cr
3. Fe
4. Zn

Answer / उत्तर: (B) Cr

Solution / समाधान:
Expected configuration of Cr is [Ar]3d⁴4s², but actual configuration is [Ar]3d⁵4s¹ because the half-filled d⁵ configuration is relatively more stable.

27. Which element has the electronic configuration [Ar]3d¹⁰4s¹?
[Ar]3d¹⁰4s¹ configuration किस element की है?

1. Cr
2. Cu
3. Zn
4. Ni

Answer / उत्तर: (B) Cu

Solution / समाधान:
[Ar] = 18; 3d¹⁰ = 10; 4s¹ = 1. Total electrons = 29 → Atomic number 29 = Cu.

28. An element belongs to the 5th period and Group 17. Its valence shell configuration is:
कोई element 5th period और Group 17 में है। उसका valence shell configuration क्या होगा?

1. 5s²5p⁵
2. 5s²5p⁶
3. 4s²4p⁵
4. 5s¹5p⁵

Answer / उत्तर: (A) 5s²5p⁵

Solution / समाधान:
Group 17 elements have ns²np⁵ configuration. For period 5, n = 5. Therefore, configuration = 5s²5p⁵.

29. Which statement about an orbital is correct?
Orbital के बारे में कौन-सा statement सही है?

1. An orbital can contain a maximum of 4 electrons.
2. An orbital can contain a maximum of 2 electrons with opposite spins.
3. An orbital always contains electrons.
4. An orbital is the same as a shell.

Answer / उत्तर: (B)

Solution / समाधान:
According to Pauli Exclusion Principle, an orbital can accommodate a maximum of two electrons and they must have opposite spins. Pauli principle के अनुसार एक orbital में maximum 2 electrons हो सकते हैं।

30. Which statement correctly explains the periodicity of properties?
Properties की periodicity को कौन-सा statement सही explain करता है?

1. Properties depend only on atomic mass.
2. Properties of elements are periodic functions of their atomic numbers.
3. Properties are independent of electronic configuration.
4. Only physical properties show periodicity.

Answer / उत्तर: (B)

Solution / समाधान:
Modern periodic law states that the physical and chemical properties of elements are periodic functions of their atomic numbers. आधुनिक आवर्त नियम के अनुसार elements के physical और chemical properties उनके atomic number के periodic functions हैं।