Determine the molarity of a solution prepared by dissolving 5.0 g of NaOH in 450 mL of solution.

1. Determine the molarity of a solution prepared by dissolving 5.0 g of NaOH in 450 mL of solution. 1. 450 mL विलयन में 5.0 g NaOH घोलकर बनाए गए विलयन की मोलरता ज्ञात कीजिए। +

Given Data

Mass of NaOH = 5.0 g
Volume of solution = 450 mL
Molar mass of NaOH = 40 g mol⁻¹

Formula

M = n / V

Where:

M = Molarity
n = Number of moles of solute
V = Volume of solution in litres

Step 1: Calculate Moles of NaOH

Number of moles:

n = Mass / Molar Mass

n = 5.0 / 40

n = 0.125 mol

Step 2: Convert Volume into Litres

Given volume = 450 mL

Since:
1000 mL = 1 L

Therefore:

V = 450 / 1000

V = 0.450 L

Step 3: Calculate Molarity

Using:

M = n / V

M = 0.125 / 0.450

M = 0.2778 mol L⁻¹

Final Answer

The molarity of the NaOH solution is approximately 0.278 M.

Quick Method

M = (Mass × 1000) / (Molar Mass × Volume in mL)

Substituting:

M = (5.0 × 1000) / (40 × 450)

M = 0.278 M

Concept

Molarity is the number of moles of solute present in one litre of solution. Therefore, the volume must always be converted from mL to L before using the formula M = n/V.

दिया गया है

NaOH का द्रव्यमान = 5.0 g
विलयन का आयतन = 450 mL
NaOH का मोलर द्रव्यमान = 40 g mol⁻¹

सूत्र

M = n / V

जहाँ:

M = मोलरता
n = विलेय के मोलों की संख्या
V = विलयन का आयतन लीटर में

चरण 1: NaOH के मोल ज्ञात कीजिए

मोलों की संख्या:

n = द्रव्यमान / मोलर द्रव्यमान

n = 5.0 / 40

n = 0.125 mol

चरण 2: आयतन को लीटर में बदलें

दिया गया आयतन = 450 mL

हम जानते हैं:
1000 mL = 1 L

इसलिए:

V = 450 / 1000

V = 0.450 L

चरण 3: मोलरता ज्ञात कीजिए

सूत्र:

M = n / V

M = 0.125 / 0.450

M = 0.2778 mol L⁻¹

अंतिम उत्तर

NaOH विलयन की मोलरता लगभग 0.278 M है।

सीधी विधि

M = (द्रव्यमान × 1000) / (मोलर द्रव्यमान × आयतन mL में)

मान रखने पर:

M = (5.0 × 1000) / (40 × 450)

M = 0.278 M

Concept

मोलरता वह संख्या है जो बताती है कि एक लीटर विलयन में विलेय के कितने मोल उपस्थित हैं। इसलिए M = n/V सूत्र में आयतन को लीटर में लेना आवश्यक है।

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30 Related MCQs 30 संबंधित MCQs

1. The molar mass of NaOH is:

A. 23 g mol⁻¹

B. 40 g mol⁻¹

C. 58.5 g mol⁻¹

D. 18 g mol⁻¹

Answer: B. 40 g mol⁻¹

2. The number of moles present in 5.0 g NaOH is:

A. 0.025 mol

B. 0.125 mol

C. 0.25 mol

D. 1.25 mol

Answer: B. 0.125 mol

3. 450 mL is equal to:

A. 4.50 L

B. 0.045 L

C. 0.450 L

D. 45.0 L

Answer: C. 0.450 L

4. The formula for molarity is:

A. M = V/n

B. M = n/V

C. M = n × V

D. M = V × mass

Answer: B. M = n/V

5. The molarity of the given NaOH solution is approximately:

A. 0.028 M

B. 0.278 M

C. 2.78 M

D. 27.8 M

Answer: B. 0.278 M

6. Molarity is expressed in:

A. mol kg⁻¹

B. mol L⁻¹

C. g L⁻¹ only

D. kg mol⁻¹

Answer: B. mol L⁻¹

7. Before calculating molarity, 450 mL should be converted into:

A. kg

B. g

C. L

D. mol

Answer: C. L

8. One mole of NaOH has a mass of:

A. 20 g

B. 30 g

C. 40 g

D. 80 g

Answer: C. 40 g

9. The atomic mass of sodium is approximately:

A. 12

B. 23

C. 35.5

D. 40

Answer: B. 23

10. The molecular mass contribution of oxygen in NaOH is:

A. 1

B. 16

C. 23

D. 40

Answer: B. 16

11. The mass contribution of hydrogen in NaOH is:

A. 1

B. 8

C. 16

D. 23

Answer: A. 1

12. If the volume of a solution increases while moles remain constant, molarity:

A. Increases

B. Decreases

C. Becomes zero immediately

D. Remains necessarily constant

Answer: B. Decreases

13. If the amount of solute increases while volume remains constant, molarity:

A. Increases

B. Decreases

C. Remains unchanged

D. Becomes zero

Answer: A. Increases

14. Which quantity is used in the numerator of the molarity formula?

A. Volume

B. Moles

C. Density

D. Temperature

Answer: B. Moles

15. Which quantity is used in the denominator of M = n/V?

A. Mass

B. Moles

C. Volume in litres

D. Molar mass

Answer: C. Volume in litres

16. 1 L is equal to:

A. 10 mL

B. 100 mL

C. 500 mL

D. 1000 mL

Answer: D. 1000 mL

17. If 0.125 mol NaOH is present in 0.450 L solution, its molarity is:

A. 0.0278 M

B. 0.278 M

C. 2.78 M

D. 27.8 M

Answer: B. 0.278 M

18. Molarity is based on the volume of:

A. Solvent only

B. Solution

C. Solute only

D. Container

Answer: B. Solution

19. The unit mol L⁻¹ can also be written as:

A. M

B. m

C. N only

D. kg

Answer: A. M

20. A 1 M solution contains:

A. 1 mole solute per litre solution

B. 1 gram solute per litre

C. 1 mole solvent per litre

D. 1 kg solute per litre

Answer: A. 1 mole solute per litre solution

21. Which formula can directly calculate molarity from mass?

A. M = mass × molar mass / volume

B. M = mass / (molar mass × volume in L)

C. M = volume / mass

D. M = molar mass / mass

Answer: B. M = mass / (molar mass × volume in L)

22. The given solution contains 0.125 mol NaOH. This quantity represents:

A. Mass

B. Number of moles

C. Volume

D. Density

Answer: B. Number of moles

23. If the same 5 g NaOH were dissolved to make 1 L solution, the molarity would be:

A. 0.0125 M

B. 0.125 M

C. 1.25 M

D. 12.5 M

Answer: B. 0.125 M

24. If the same 5 g NaOH were dissolved to make 0.225 L solution, the molarity would be:

A. 0.278 M

B. 0.556 M

C. 1.11 M

D. 2.22 M

Answer: B. 0.556 M

25. Molarity changes with temperature mainly because:

A. Number of atoms changes

B. Volume of solution may change

C. Molar mass changes

D. Atomic number changes

Answer: B. Volume of solution may change

26. Which is NOT needed directly to calculate molarity from mass?

A. Mass of solute

B. Molar mass

C. Volume of solution

D. Atomic number of solvent

Answer: D. Atomic number of solvent

27. The molarity calculated for the given solution to three significant figures is:

A. 0.278 M

B. 0.28 M

C. 2.78 M

D. 27.8 M

Answer: A. 0.278 M

28. In a dilution process, if moles remain constant and volume increases, concentration:

A. Increases

B. Decreases

C. Becomes infinite

D. Always remains unchanged

Answer: B. Decreases

29. The value 0.278 M means approximately:

A. 0.278 mol NaOH per litre solution

B. 0.278 g NaOH per litre

C. 2.78 mol NaOH per litre

D. 278 mol NaOH per litre

Answer: A. 0.278 mol NaOH per litre solution

30. The correct final answer for the given problem is:

A. 0.0278 M

B. 0.278 M

C. 2.78 M

D. 27.8 M

Answer: B. 0.278 M

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How does the Henry’s Law constant (KH​) relate to the solubility of a gas in a liquid?

1. How does the Henry’s Law constant (K_H) relate to the solubility of a gas in a liquid? 1. हेनरी के नियम नियतांक (K_H) का किसी द्रव में गैस की विलेयता से क्या संबंध है? +

Detailed Answer

The Henry’s Law constant (K_H) expresses the relationship between the partial pressure of a gas above a liquid and the amount of that gas dissolved in the liquid at a particular temperature.

P = K_Hx

Where:

P = partial pressure of the gas
K_H = Henry’s Law constant
x = mole fraction of the dissolved gas

Relation with Solubility

From the equation:

P = K_Hx

we get:

x = P / K_H

At constant pressure, the solubility of the gas is inversely proportional to K_H.

Therefore:

Higher K_H → Lower solubility
Lower K_H → Higher solubility

K_H ↑ → Solubility ↓

K_H ↓ → Solubility ↑

Why?

If K_H is large, a greater gas pressure is required to maintain the same dissolved concentration. Hence, the gas has a lower tendency to remain dissolved in the liquid.

If K_H is small, a relatively small pressure can maintain a larger amount of dissolved gas. Thus, the gas is more soluble.

Example

Consider two gases at the same temperature:

Gas A: K_H = 20 atm
Gas B: K_H = 50 atm

At the same pressure, Gas A will have greater solubility because its K_H value is smaller.

Effect of Temperature

For most gases, solubility decreases as temperature increases. In the convention P = K_Hx, K_H generally increases with temperature.

Temperature ↑ → K_H ↑ → Solubility ↓

Important Note

Different textbooks may use different definitions of Henry’s Law constant. For example, if the equation is written as:

C = kP

then a larger value of k means greater solubility. Therefore, always check the equation used to define the constant before interpreting its numerical value.

Final Answer

For the convention P = K_Hx, Henry’s Law constant is inversely related to the solubility of a gas. At constant pressure, x = P/K_H. Therefore, a higher K_H means lower gas solubility, while a lower K_H means higher gas solubility.

विस्तृत उत्तर

Henry’s Law constant (K_H) गैस के आंशिक दाब और द्रव में घुली हुई गैस की मात्रा के बीच संबंध बताता है। यह संबंध एक निश्चित तापमान पर लागू होता है।

P = K_Hx

जहाँ:

P = गैस का आंशिक दाब
K_H = Henry’s Law constant
x = द्रव में घुली गैस का mole fraction

विलेयता से संबंध

समीकरण:

P = K_Hx

से:

x = P / K_H

स्थिर दाब पर गैस की विलेयता K_H के व्युत्क्रमानुपाती होती है।

अर्थात:

अधिक K_H → कम विलेयता
कम K_H → अधिक विलेयता

K_H ↑ → विलेयता ↓

K_H ↓ → विलेयता ↑

ऐसा क्यों होता है?

यदि K_H का मान अधिक है, तो समान मात्रा में गैस को द्रव में घुलाए रखने के लिए अधिक गैस दाब की आवश्यकता होती है। इसलिए गैस की द्रव में विलेयता कम होती है।

यदि K_H का मान कम है, तो कम दाब पर भी अधिक गैस द्रव में घुली रह सकती है। इसलिए गैस अधिक soluble होती है।

उदाहरण

समान तापमान पर:

Gas A: K_H = 20 atm
Gas B: K_H = 50 atm

समान pressure पर Gas A की विलेयता अधिक होगी क्योंकि उसका K_H कम है।

तापमान का प्रभाव

अधिकांश गैसों की विलेयता तापमान बढ़ने पर कम होती है। P = K_Hx वाले convention में तापमान बढ़ने पर सामान्यतः K_H बढ़ता है।

तापमान ↑ → K_H ↑ → गैस की विलेयता ↓

महत्वपूर्ण नोट

अलग-अलग पुस्तकों में Henry’s Law constant को अलग-अलग तरीके से define किया जा सकता है।

उदाहरण:

C = kP

इस convention में k का अधिक मान अधिक gas solubility को दर्शाता है। इसलिए numerical question में पहले यह देखना आवश्यक है कि K_H किस equation द्वारा define किया गया है।

अंतिम उत्तर

P = K_Hx वाले convention में Henry’s Law constant गैस की विलेयता के व्युत्क्रमानुपाती होता है। स्थिर दाब पर x = P/K_H होता है। इसलिए अधिक K_H का अर्थ कम गैस विलेयता तथा कम K_H का अर्थ अधिक गैस विलेयता है।

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30 Related MCQs 30 संबंधित MCQs

1. Henry’s Law constant is represented by:

A. K_H

B. K_a

C. K_b

D. K_w

Answer: A. K_H

2. In P = K_Hx, x represents:

A. Pressure

B. Mole fraction of dissolved gas

C. Temperature

D. Volume

Answer: B. Mole fraction of dissolved gas

3. From P = K_Hx, x is:

A. P/K_H

B. PK_H

C. K_H/P

D. P + K_H

Answer: A. P/K_H

4. At constant pressure, increasing K_H causes solubility to:

A. Increase

B. Decrease

C. Remain constant

D. Become infinite

Answer: B. Decrease

5. At constant pressure, decreasing K_H causes solubility to:

A. Increase

B. Decrease

C. Become zero

D. Remain unchanged

Answer: A. Increase

6. In P = K_Hx, K_H and solubility are:

A. Directly related

B. Inversely related

C. Always equal

D. Unrelated

Answer: B. Inversely related

7. A gas with lower K_H is generally:

A. More soluble

B. Less soluble

C. Insoluble

D. Solid

Answer: A. More soluble

8. A gas with higher K_H requires what for the same dissolved concentration?

A. Higher pressure

B. Lower pressure

C. Zero pressure

D. No pressure

Answer: A. Higher pressure

9. Henry’s Law connects gas solubility with:

A. Partial pressure

B. Atomic radius

C. Ionisation energy

D. Electronegativity

Answer: A. Partial pressure

10. The solubility of most gases with increasing temperature:

A. Increases

B. Decreases

C. Remains unchanged

D. Becomes infinite

Answer: B. Decreases

11. In P = K_Hx convention, temperature increase generally causes K_H to:

A. Increase

B. Decrease

C. Become zero

D. Become independent of temperature

Answer: A. Increase

12. Which gas is commonly used as an example in carbonated drinks?

A. CO₂

B. NaCl

C. CaO

D. Fe

Answer: A. CO₂

13. If P is doubled and K_H remains constant, x will:

A. Double

B. Halve

C. Become zero

D. Remain unchanged

Answer: A. Double

14. If K_H is doubled at constant P, x will:

A. Double

B. Become half

C. Become four times

D. Remain unchanged

Answer: B. Become half

15. Henry’s Law is generally considered at:

A. Constant temperature

B. Constant atomic number

C. Constant neutron number

D. Zero pressure

Answer: A. Constant temperature

16. Which equation is the mole-fraction form of Henry’s Law?

A. P = K_Hx

B. P = x/K_H

C. x = PK_H

D. P = x²

Answer: A. P = K_Hx

17. At constant pressure, x is proportional to:

A. K_H

B. 1/K_H

C. K_H²

D. Zero

Answer: B. 1/K_H

18. Henry’s Law constant depends on:

A. Temperature

B. Nature of gas

C. Nature of solvent

D. All of these

Answer: D. All of these

19. A lower K_H generally indicates:

A. Greater gas solubility

B. Lower gas solubility

C. No dissolution

D. Gas solidification

Answer: A. Greater gas solubility

20. In P = K_Hx, P represents:

A. Partial pressure

B. Mole fraction

C. Temperature

D. Mass

Answer: A. Partial pressure

21. If Gas A has K_H = 10 and Gas B has K_H = 40, which is more soluble?

A. Gas A

B. Gas B

C. Both equally

D. Cannot ever dissolve

Answer: A. Gas A

22. Which change generally increases gas solubility?

A. Increase pressure

B. Increase temperature

C. Decrease pressure

D. Boil the solution

Answer: A. Increase pressure

23. In the convention P = K_Hx, K_H is best described as:

A. Pressure required per unit mole fraction

B. Temperature per mole

C. Mass per volume

D. Density constant

Answer: A. Pressure required per unit mole fraction

24. Which statement is correct?

A. Higher K_H means higher solubility in every convention

B. The equation defining K_H must be checked

C. K_H is always dimensionless

D. K_H is independent of temperature

Answer: B. The equation defining K_H must be checked

25. In C = kP convention, a larger k means:

A. Higher solubility

B. Lower solubility

C. No solubility

D. Zero concentration

Answer: A. Higher solubility

26. Gas solubility is generally higher when temperature is:

A. Lower

B. Higher

C. Infinite

D. Always irrelevant

Answer: A. Lower

27. A high K_H gas has:

A. Greater tendency to dissolve

B. Lower solubility under P = K_Hx convention

C. Infinite solubility

D. No pressure requirement

Answer: B. Lower solubility under P = K_Hx convention

28. Which statement follows from x = P/K_H?

A. Increasing pressure increases solubility

B. Increasing K_H increases solubility

C. Pressure has no effect

D. K_H is equal to x

Answer: A. Increasing pressure increases solubility

29. The value of K_H can change when:

A. Temperature changes

B. The gas changes

C. The solvent changes

D. All of these

Answer: D. All of these

30. For P = K_Hx, the correct relationship is:

A. K_H ↑ → Solubility ↑

B. K_H ↑ → Solubility ↓

C. K_H has no effect

D. Solubility is always zero

Answer: B. K_H ↑ → Solubility ↓

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How does the Henry’s Law constant (KH​) relate to the solubility of a gas in a liquid?

1. How does the Henry’s Law constant (K_H) relate to the solubility of a gas in a liquid? 1. हेनरी के नियम नियतांक (K_H) का किसी द्रव में गैस की विलेयता से क्या संबंध है? +

Detailed Explanation

The Henry’s Law constant (K_H) is a constant that relates the partial pressure of a gas above a liquid to the concentration or solubility of that gas dissolved in the liquid at a particular temperature. For the commonly used form of Henry’s Law:

P = K_H × x

Where:

P = partial pressure of the gas above the solution
K_H = Henry’s Law constant
x = mole fraction of the dissolved gas

Therefore:

K_H = P / x

Relation Between K_H and Solubility

For the above convention of Henry’s Law, the relationship is:

Higher K_H → Lower solubility of the gas

Lower K_H → Higher solubility of the gas

Thus, Henry’s Law constant is inversely related to gas solubility when the equation P = K_Hx is used.

K_H ↑ → Solubility ↓

K_H ↓ → Solubility ↑

Why Does Higher K_H Mean Lower Solubility?

From:
P = K_Hx

we can rearrange:
x = P / K_H

At a fixed pressure, if K_H increases, x decreases. Since x represents the amount of gas dissolved in the liquid, a smaller x means lower solubility.

Example

Suppose two gases have the following Henry’s Law constants at the same temperature:

Gas A: K_H = 20 atm
Gas B: K_H = 50 atm

At the same partial pressure, Gas A will have greater solubility because its K_H value is lower.

Lower K_H → More gas dissolves
Higher K_H → Less gas dissolves

Important Note About Different Conventions

Henry’s Law is written in different forms in different textbooks and scientific sources. For example:

P = K_Hx

uses K_H as a pressure/mole-fraction constant, for which a higher K_H means lower solubility.

Another convention may define the constant as the ratio of dissolved concentration to pressure:

C = kP

In that convention, a larger k means greater solubility.

Therefore, always check the exact equation used to define the Henry’s Law constant before comparing numerical values.

Connection with Temperature

For most gases, increasing temperature decreases their solubility. Therefore, under the convention:

P = K_Hx

the Henry’s Law constant generally increases with increasing temperature. Thus:

Temperature ↑
→ K_H ↑
→ Gas Solubility ↓

Final Answer

For the commonly used form P = K_Hx, the Henry’s Law constant is inversely related to the solubility of a gas. At a given pressure, x = P/K_H. Therefore, a larger K_H means lower solubility, whereas a smaller K_H means higher solubility. The exact meaning depends on the convention used to define K_H.

विस्तृत व्याख्या

Henry’s Law Constant (K_H) वह नियतांक है जो किसी द्रव में घुली गैस की मात्रा तथा द्रव के ऊपर उपस्थित गैस के आंशिक दाब के बीच संबंध बताता है। Henry’s Law का एक सामान्य रूप है:

P = K_H × x

जहाँ:

P = गैस का आंशिक दाब
K_H = Henry’s Law constant
x = द्रव में घुली गैस का mole fraction

इससे:

K_H = P / x

K_H और गैस की विलेयता का संबंध

ऊपर दिए गए Henry’s Law के convention में:

अधिक K_H → कम विलेयता

कम K_H → अधिक विलेयता

अर्थात P = K_Hx वाले convention में Henry’s Law constant गैस की विलेयता के व्युत्क्रमानुपाती होता है।

K_H ↑ → विलेयता ↓

K_H ↓ → विलेयता ↑

अधिक K_H का अर्थ कम विलेयता क्यों?

Henry’s Law:

P = K_Hx

को rearrange करने पर:

x = P / K_H

स्थिर दाब पर यदि K_H बढ़ता है, तो x का मान कम हो जाता है। चूँकि x द्रव में घुली गैस की मात्रा को दर्शाता है, इसलिए x का कम होना गैस की कम विलेयता को दर्शाता है।

उदाहरण

मान लीजिए समान तापमान पर दो गैसों के Henry’s Law constants हैं:

Gas A: K_H = 20 atm
Gas B: K_H = 50 atm

समान partial pressure पर Gas A की विलेयता अधिक होगी क्योंकि उसका K_H कम है।

कम K_H → अधिक गैस घुलेगी
अधिक K_H → कम गैस घुलेगी

महत्वपूर्ण नोट: अलग-अलग Convention

अलग-अलग Chemistry textbooks और scientific sources में Henry’s Law को अलग-अलग रूपों में लिखा जा सकता है।

एक रूप:

P = K_Hx

इसमें K_H अधिक होने का अर्थ सामान्यतः गैस की कम विलेयता है।

दूसरा रूप:

C = kP

इस convention में k अधिक होने का अर्थ गैस की अधिक विलेयता है।

इसलिए numerical question हल करते समय यह देखना बहुत जरूरी है कि Henry’s Law constant को किस equation द्वारा define किया गया है।

तापमान से संबंध

अधिकांश गैसों की विलेयता तापमान बढ़ने पर कम होती है। इसलिए यदि:

P = K_Hx

वाला convention इस्तेमाल किया जाए, तो सामान्यतः तापमान बढ़ने पर K_H बढ़ता है।

तापमान ↑
→ K_H ↑
→ गैस की विलेयता ↓

अंतिम उत्तर

P = K_Hx वाले सामान्य convention में Henry’s Law constant गैस की विलेयता के व्युत्क्रमानुपाती होता है। स्थिर दाब पर x = P/K_H होता है। इसलिए अधिक K_H का अर्थ कम गैस की विलेयता और कम K_H का अर्थ अधिक गैस की विलेयता है। हालांकि K_H की परिभाषा अलग convention में अलग हो सकती है, इसलिए equation को देखकर ही इसका संबंध तय करना चाहिए।

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30 Related MCQs 30 संबंधित बहुविकल्पीय प्रश्न

1. Henry’s Law relates gas solubility mainly to:

A. Atomic number

B. Partial pressure

C. Neutron number

D. Density only

Answer: B. Partial pressure

2. In P = K_Hx, K_H represents:

A. Gas concentration

B. Henry’s Law constant

C. Solvent mass

D. Temperature

Answer: B. Henry’s Law constant

3. In P = K_Hx, x represents:

A. Pressure

B. Mole fraction of dissolved gas

C. Temperature

D. Volume

Answer: B. Mole fraction of dissolved gas

4. From P = K_Hx, x is equal to:

A. P × K_H

B. P/K_H

C. K_H/P

D. P + K_H

Answer: B. P/K_H

5. At constant pressure, if K_H increases, solubility:

A. Increases

B. Decreases

C. Remains unchanged

D. Becomes infinite

Answer: B. Decreases

6. A gas having a smaller K_H value in P = K_Hx form is:

A. More soluble

B. Less soluble

C. Completely insoluble

D. Always solid

Answer: A. More soluble

7. The relation between K_H and x at constant P is:

A. Direct

B. Inverse

C. Exponential

D. Constant

Answer: B. Inverse

8. If K_H is doubled at constant pressure, x becomes:

A. Double

B. Half

C. Four times

D. Unchanged

Answer: B. Half

9. Which gas is commonly discussed using Henry’s Law in soft drinks?

A. CO₂

B. NaCl

C. CaCO₃

D. HCl solid

Answer: A. CO₂

10. In the convention P = K_Hx, high K_H indicates:

A. High solubility

B. Low solubility

C. No relation

D. Infinite solubility

Answer: B. Low solubility

11. The Henry’s Law constant depends on:

A. Nature of gas and solvent

B. Temperature

C. Both A and B

D. Atomic number only

Answer: C. Both A and B

12. For most gases, increasing temperature generally:

A. Increases solubility

B. Decreases solubility

C. Has no effect

D. Converts gas to metal

Answer: B. Decreases solubility

13. Under P = K_Hx convention, increasing temperature generally causes K_H to:

A. Increase

B. Decrease

C. Become zero

D. Remain universally constant

Answer: A. Increase

14. Henry’s Law is generally applied at:

A. Constant temperature

B. Constant atomic number

C. Constant neutron number

D. Zero pressure

Answer: A. Constant temperature

15. If K_H is small, gas solubility in P = K_Hx form is:

A. Relatively high

B. Relatively low

C. Zero

D. Impossible to determine

Answer: A. Relatively high

16. Which equation correctly represents the commonly used mole-fraction form?

A. P = K_Hx

B. P = x/K_H

C. x = PK_H

D. P = x²

Answer: A. P = K_Hx

17. If P remains constant and K_H decreases, x:

A. Increases

B. Decreases

C. Becomes zero

D. Remains unchanged

Answer: A. Increases

18. Which statement is correct for P = K_Hx?

A. K_H is directly proportional to solubility

B. K_H is inversely related to solubility

C. K_H has no relation to solubility

D. K_H is always zero

Answer: B. K_H is inversely related to solubility

19. Which factor increases gas solubility at constant temperature?

A. Decreasing partial pressure

B. Increasing partial pressure

C. Increasing K_H only

D. Heating always

Answer: B. Increasing partial pressure

20. The unit of K_H in P = K_Hx depends on:

A. The pressure unit used

B. Atomic number

C. Neutron number

D. Colour of solution

Answer: A. The pressure unit used

21. Henry’s Law constant is a property of:

A. Gas-solvent system

B. Solute only

C. Container only

D. Thermometer only

Answer: A. Gas-solvent system

22. In P = K_Hx, if x increases at constant K_H, P:

A. Increases

B. Decreases

C. Becomes zero

D. Remains unchanged

Answer: A. Increases

23. A gas with high K_H in the P = K_Hx convention requires:

A. Higher pressure for the same dissolved concentration

B. Lower pressure for the same concentration

C. No pressure

D. Zero temperature

Answer: A. Higher pressure for the same dissolved concentration

24. Which factor can change the value of K_H?

A. Temperature

B. Nature of solvent

C. Nature of gas

D. All of these

Answer: D. All of these

25. In the equation C = kP, a larger k indicates:

A. Greater gas solubility

B. Lower gas solubility

C. Zero solubility

D. No solubility

Answer: A. Greater gas solubility

26. Why must the equation defining K_H be checked before comparing values?

A. Different conventions are used

B. K_H is always zero

C. Pressure has no unit

D. Temperature is irrelevant

Answer: A. Different conventions are used

27. At constant pressure, x = P/K_H shows that x is:

A. Directly proportional to K_H

B. Inversely proportional to K_H

C. Independent of K_H

D. Equal to K_H

Answer: B. Inversely proportional to K_H

28. If Gas A has lower K_H than Gas B under the same convention and temperature, Gas A is:

A. More soluble

B. Less soluble

C. Equally soluble always

D. Insoluble

Answer: A. More soluble

29. Which statement about Henry’s Law is most accurate?

A. It relates gas pressure and dissolved gas concentration

B. It relates atomic mass and pressure

C. It applies only to solids

D. It states that all gases have identical solubility

Answer: A. It relates gas pressure and dissolved gas concentration

30. In the convention P = K_Hx, the correct relationship is:

A. K_H ↑ → Solubility ↑

B. K_H ↑ → Solubility ↓

C. K_H ↑ → Pressure ↓ necessarily

D. K_H has no connection with solubility

Answer: B. K_H ↑ → Solubility ↓

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Define Henry’s Law and explain why the solubility of a gas decreases with increasing temperature.

1. Define Henry’s Law and explain why the solubility of a gas decreases with increasing temperature. 1. हेनरी के नियम को परिभाषित कीजिए तथा समझाइए कि तापमान बढ़ने पर गैस की विलेयता क्यों कम हो जाती है। +

Detailed Answer

Henry’s Law states that at constant temperature, the solubility of a gas in a liquid is directly proportional to the partial pressure of that gas above the solution.

C ∝ P

C = k_HP

Where:

C = concentration or solubility of the dissolved gas
P = partial pressure of the gas
k_H = Henry’s law constant

Thus, if the partial pressure of a gas increases, more gas dissolves in the liquid, provided the temperature remains constant.

Effect of Temperature on Gas Solubility

The solubility of most gases in liquids decreases when temperature increases.

This happens mainly because the dissolution of gases in liquids is generally an exothermic process. When the temperature is increased, heat is supplied to the system.

According to Le Chatelier’s principle, the equilibrium shifts in the direction that absorbs the added heat. Therefore, the dissolved gas tends to escape from the liquid into the gaseous phase.

Temperature ↑
↓
Kinetic energy of gas molecules ↑
↓
Gas molecules escape more easily from the liquid
↓
Gas solubility ↓

Molecular Explanation

At higher temperatures, gas molecules possess greater kinetic energy. Therefore, the molecules move more rapidly and are more likely to overcome the attractive forces holding them in the liquid.

As a result, more dissolved gas molecules leave the liquid and enter the gas phase. Hence, the equilibrium concentration of the dissolved gas decreases.

Example

Carbon dioxide is much more soluble in cold water than in warm water. Therefore, cold carbonated drinks retain dissolved CO₂ better than warm drinks.

When a carbonated drink is warmed, CO₂ escapes more rapidly, which is why the drink loses its fizz.

Important Exception

The statement that gas solubility decreases with increasing temperature applies to most gases. The exact temperature dependence can vary depending on the gas, solvent and pressure conditions.

Final Answer

Henry’s Law states that at constant temperature, the solubility of a gas in a liquid is directly proportional to its partial pressure: C = k_HP. The solubility of most gases decreases with increasing temperature because gas dissolution is generally exothermic. Heating gives gas molecules more kinetic energy, causing them to escape more readily from the liquid into the gas phase. Therefore, the amount of dissolved gas decreases.

विस्तृत उत्तर

हेनरी का नियम (Henry’s Law) कहता है कि स्थिर तापमान पर किसी द्रव में घुली हुई गैस की विलेयता उस गैस के द्रव के ऊपर उपस्थित आंशिक दाब के समानुपाती होती है।

C ∝ P

C = k_HP

जहाँ:

C = द्रव में घुली गैस की सांद्रता/विलेयता
P = गैस का आंशिक दाब
k_H = हेनरी नियम नियतांक

अर्थात यदि तापमान स्थिर हो और गैस का आंशिक दाब बढ़ाया जाए, तो अधिक मात्रा में गैस द्रव में घुलेगी।

तापमान बढ़ने पर गैस की विलेयता क्यों घटती है?

अधिकांश गैसों की द्रवों में विलेयता तापमान बढ़ने पर कम हो जाती है।

इसका मुख्य कारण यह है कि गैसों का द्रव में घुलना सामान्यतः ऊष्माक्षेपी (exothermic) प्रक्रिया होती है। जब तापमान बढ़ाया जाता है, तो सिस्टम को ऊष्मा प्रदान की जाती है।

Le Chatelier के सिद्धांत के अनुसार equilibrium अतिरिक्त ऊष्मा के प्रभाव को कम करने वाली दिशा में shift करता है। इसलिए घुली हुई गैस द्रव से बाहर निकलकर गैसीय अवस्था में जाने लगती है।

तापमान ↑
↓
गैस अणुओं की गतिज ऊर्जा ↑
↓
अणु द्रव से आसानी से बाहर निकलते हैं
↓
गैस की विलेयता ↓

आणविक कारण

तापमान बढ़ने पर गैस के अणुओं की गतिज ऊर्जा बढ़ जाती है। इसके कारण अणु अधिक तेजी से गति करते हैं और द्रव में उन्हें रोकने वाले आकर्षण बलों को आसानी से पार कर सकते हैं।

इसलिए अधिक संख्या में घुले हुए गैस अणु द्रव से निकलकर गैस अवस्था में चले जाते हैं। परिणामस्वरूप द्रव में घुली गैस की मात्रा कम हो जाती है।

उदाहरण

ठंडे पानी में CO₂ की विलेयता गर्म पानी की तुलना में अधिक होती है। इसलिए cold carbonated drinks में CO₂ अधिक समय तक घुली रहती है।

जब carbonated drink को गर्म किया जाता है, तो CO₂ तेजी से बाहर निकलती है और drink की fizz कम हो जाती है।

महत्वपूर्ण बात

तापमान बढ़ने पर गैस की विलेयता घटने का नियम अधिकांश गैसों पर लागू होता है। वास्तविक प्रभाव गैस, विलायक और दबाव की परिस्थितियों पर निर्भर कर सकता है।

अंतिम उत्तर

हेनरी का नियम कहता है कि स्थिर तापमान पर द्रव में गैस की विलेयता उसके आंशिक दाब के समानुपाती होती है: C = k_HP. अधिकांश गैसों की विलेयता तापमान बढ़ने पर कम हो जाती है क्योंकि गैस का द्रव में घुलना सामान्यतः ऊष्माक्षेपी प्रक्रिया है। तापमान बढ़ने पर गैस अणुओं की गतिज ऊर्जा बढ़ती है और वे द्रव से अधिक आसानी से बाहर निकलते हैं। इसलिए द्रव में घुली गैस की मात्रा कम हो जाती है।

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30 Related MCQs 30 संबंधित बहुविकल्पीय प्रश्न

1. Henry’s Law relates the solubility of a gas to its:

A. Atomic mass

B. Partial pressure

C. Density

D. Melting point

Answer: B. Partial pressure

2. The mathematical expression of Henry’s Law is:

A. C = k_HP

B. PV = nRT

C. P = k/C

D. C = P²

Answer: A. C = k_HP

3. According to Henry’s Law, gas solubility increases when pressure:

A. Decreases

B. Increases

C. Becomes zero

D. Remains irrelevant

Answer: B. Increases

4. The solubility of most gases in liquids with increasing temperature:

A. Increases

B. Decreases

C. Remains exactly constant

D. Becomes infinite

Answer: B. Decreases

5. Dissolution of most gases in liquids is generally:

A. Endothermic

B. Exothermic

C. Nuclear

D. Photochemical

Answer: B. Exothermic

6. When temperature increases, gas molecules acquire:

A. Less kinetic energy

B. More kinetic energy

C. No energy

D. Constant zero energy

Answer: B. More kinetic energy

7. Carbon dioxide is more soluble in:

A. Warm water

B. Cold water

C. Boiling water

D. Hot oil

Answer: B. Cold water

8. Warm carbonated drinks lose CO₂ faster because:

A. Gas solubility increases

B. Gas solubility decreases

C. Pressure becomes infinite

D. CO₂ becomes solid

Answer: B. Gas solubility decreases

9. Henry’s Law is applicable at:

A. Constant temperature

B. Constant atomic number

C. Constant mass only

D. Zero pressure only

Answer: A. Constant temperature

10. k_H represents:

A. Henry’s law constant

B. Heat constant

C. Hydrogen constant

D. Kinetic constant

Answer: A. Henry’s law constant

11. Increasing the partial pressure of a gas generally causes its solubility to:

A. Increase

B. Decrease

C. Become zero

D. Remain unaffected

Answer: A. Increase

12. Which principle explains the effect of heat on an equilibrium involving gas dissolution?

A. Le Chatelier’s principle

B. Avogadro’s law

C. Graham’s law

D. Dalton’s law

Answer: A. Le Chatelier’s principle

13. On heating a gas-liquid solution, dissolved gas tends to:

A. Remain completely dissolved

B. Escape into the gas phase

C. Become a solid

D. React with all water molecules

Answer: B. Escape into the gas phase

14. Which gas is commonly used as an example of gas solubility in soft drinks?

A. CO₂

B. He

C. Ne

D. Ar

Answer: A. CO₂

15. The dissolved gas concentration is represented by:

A. C

B. P

C. T

D. V

Answer: A. C

16. If P doubles at constant temperature, according to Henry’s Law C will:

A. Halve

B. Double

C. Become zero

D. Remain unchanged

Answer: B. Double

17. The solubility of gases generally decreases because heating:

A. Reduces molecular motion

B. Increases molecular motion

C. Removes all solvent

D. Changes gas into a metal

Answer: B. Increases molecular motion

18. Which statement is correct?

A. Gas solubility always increases with temperature

B. Most gases become less soluble on heating

C. Gas solubility is independent of pressure

D. Henry’s Law applies only to solids

Answer: B. Most gases become less soluble on heating

19. A cold soft drink retains more CO₂ because:

A. CO₂ is more soluble at lower temperature

B. CO₂ becomes a solid

C. Water disappears

D. Pressure is always zero

Answer: A. CO₂ is more soluble at lower temperature

20. Heating a carbonated beverage causes:

A. More CO₂ dissolution

B. Faster CO₂ escape

C. Formation of nitrogen

D. Formation of oxygen

Answer: B. Faster CO₂ escape

21. Henry’s Law connects gas solubility with:

A. Partial pressure

B. Atomic radius

C. Ionization energy

D. Electronegativity

Answer: A. Partial pressure

22. The symbol P in Henry’s Law represents:

A. Temperature

B. Partial pressure

C. Mass

D. Volume

Answer: B. Partial pressure

23. Increasing temperature generally favours:

A. Retention of dissolved gas

B. Escape of dissolved gas

C. Solidification of gas

D. Formation of solvent

Answer: B. Escape of dissolved gas

24. Gas solubility is generally higher at:

A. Higher temperature

B. Lower temperature

C. Infinite temperature

D. Boiling point only

Answer: B. Lower temperature

25. The process of gas dissolving in liquid is generally:

A. Exothermic

B. Endothermic

C. Nuclear fission

D. Combustion

Answer: A. Exothermic

26. If gas pressure above a liquid is reduced, its solubility generally:

A. Increases

B. Decreases

C. Becomes infinite

D. Becomes independent of pressure

Answer: B. Decreases

27. Which factor does not directly appear in the simple Henry’s Law expression C = k_HP?

A. Gas partial pressure

B. Henry’s constant

C. Gas concentration

D. Atomic number

Answer: D. Atomic number

28. Why do gas molecules escape more easily at higher temperature?

A. Their kinetic energy increases

B. Their mass becomes zero

C. Their atomic number decreases

D. They become liquids

Answer: A. Their kinetic energy increases

29. Which statement about Henry’s Law is correct?

A. It states that gas solubility is proportional to partial pressure at constant temperature

B. It states that gas solubility is proportional to atomic number

C. It applies only to metals

D. It states that pressure has no effect

Answer: A. It states that gas solubility is proportional to partial pressure at constant temperature

30. The best reason for decreased gas solubility on heating is:

A. Gas molecules gain kinetic energy and escape from the liquid more readily

B. Gas molecules lose all kinetic energy

C. Pressure becomes zero in every case

D. Solvent mass becomes zero

Answer: A. Gas molecules gain kinetic energy and escape from the liquid more readily

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Explain why scuba divers use air diluted with helium to avoid the painful condition known as 'bends

1. Explain why scuba divers use air diluted with helium to avoid the painful condition known as 'bends'. 1. समझाइए कि स्कूबा डाइवर्स 'बेंड्स' नामक दर्दनाक स्थिति से बचने के लिए हीलियम से पतली की गई हवा का उपयोग क्यों करते हैं। +

Detailed Answer

Scuba divers breathe compressed air while diving deep underwater. This air usually contains nitrogen and oxygen. At great depths, the surrounding pressure becomes very high.

According to Henry's law, the solubility of a gas in a liquid increases when the pressure of that gas increases. Therefore, under high pressure, more nitrogen from the breathing air dissolves in the diver's blood and body tissues.

What happens during rapid ascent?

When a diver returns to the surface too quickly, the external pressure decreases rapidly. The nitrogen dissolved in the blood and tissues then comes out of solution and forms tiny gas bubbles.

These nitrogen bubbles can block blood vessels and damage tissues. They may cause severe pain in joints and muscles, breathing difficulty, dizziness, and other serious symptoms. This condition is called decompression sickness, commonly known as the 'bends'.

Why is Helium used?

Helium is used instead of a large proportion of nitrogen because helium is much less soluble in blood and body tissues than nitrogen.

Therefore, when helium is used in the breathing mixture, much less inert gas dissolves in the diver's tissues at high pressure.

During ascent, there is consequently a much smaller tendency for gas bubbles to form.

High Pressure → More N₂ dissolves in tissues
Rapid Ascent → N₂ bubbles form → Bends

Helium mixture → Less dissolved inert gas → Lower risk of bends

Why not simply use pure oxygen?

Pure oxygen is not normally used for deep diving because oxygen itself can become toxic at sufficiently high partial pressures. Therefore, specially prepared breathing mixtures such as helium–oxygen (Heliox) may be used for deep diving.

Helium is also chemically inert and has a low density, which makes breathing easier at great depths.

Role of Henry's Law

Henry's law explains the basic reason behind the bends:

At constant temperature, the solubility of a gas in a liquid is directly proportional to the partial pressure of that gas above the liquid.

C ∝ P
or
C = kP

Final Answer

Scuba divers use helium-diluted air because helium is less soluble in blood and tissues than nitrogen. At high pressure, less helium dissolves in the body, and during ascent there is less formation of gas bubbles. This reduces the risk of decompression sickness, commonly called the 'bends'.

विस्तृत उत्तर

स्कूबा डाइवर्स जब पानी के अंदर गहराई तक जाते हैं, तो वे संपीडित हवा (compressed air) में सांस लेते हैं। इस हवा में मुख्यतः नाइट्रोजन और ऑक्सीजन होती है। अधिक गहराई पर पानी का दबाव बहुत अधिक हो जाता है।

हेनरी के नियम (Henry's Law) के अनुसार किसी द्रव में गैस की विलेयता उस गैस के आंशिक दाब के बढ़ने पर बढ़ती है। इसलिए अधिक दबाव पर सांस लेने वाली हवा का अधिक नाइट्रोजन रक्त और शरीर के ऊतकों में घुल जाता है।

तेजी से ऊपर आने पर क्या होता है?

यदि गोताखोर बहुत तेजी से पानी की सतह की ओर आता है, तो बाहरी दबाव तेजी से कम हो जाता है। शरीर के ऊतकों और रक्त में घुला हुआ नाइट्रोजन गैस के रूप में बाहर निकलने लगता है और छोटे-छोटे बुलबुले बना सकता है।

ये नाइट्रोजन के बुलबुले रक्त वाहिकाओं को अवरुद्ध कर सकते हैं और ऊतकों को नुकसान पहुँचा सकते हैं। इससे जोड़ों और मांसपेशियों में तेज दर्द, चक्कर, सांस लेने में कठिनाई तथा अन्य गंभीर समस्याएँ हो सकती हैं। इस स्थिति को Decompression Sickness या सामान्य रूप से 'Bends' कहते हैं।

हीलियम का उपयोग क्यों किया जाता है?

हीलियम का उपयोग नाइट्रोजन के एक बड़े भाग के स्थान पर किया जाता है क्योंकि हीलियम रक्त और शरीर के ऊतकों में नाइट्रोजन की तुलना में बहुत कम घुलता है।

इसलिए उच्च दबाव पर शरीर में कम मात्रा में inert gas घुलती है। जब गोताखोर ऊपर आता है, तो गैस के बुलबुले बनने की संभावना कम हो जाती है।

अधिक दबाव → अधिक N₂ ऊतकों में घुलता है
तेजी से ऊपर आना → N₂ के बुलबुले → Bends

Helium mixture → कम घुली हुई inert gas → Bends का कम जोखिम

शुद्ध ऑक्सीजन का उपयोग क्यों नहीं?

बहुत अधिक गहराई पर ऑक्सीजन का आंशिक दाब बढ़ जाता है। पर्याप्त अधिक partial pressure पर ऑक्सीजन toxic प्रभाव उत्पन्न कर सकती है। इसलिए deep diving में उपयुक्त breathing mixtures, जैसे Heliox (helium + oxygen), का उपयोग किया जा सकता है।

हीलियम एक रासायनिक रूप से निष्क्रिय गैस है और इसकी density कम होने के कारण अधिक गहराई पर सांस लेना भी अपेक्षाकृत आसान होता है।

हेनरी के नियम की भूमिका

हेनरी का नियम bends को समझने में महत्वपूर्ण है। इसके अनुसार स्थिर तापमान पर किसी द्रव में गैस की विलेयता उस गैस के आंशिक दाब के समानुपाती होती है।

C ∝ P
या
C = kP

अंतिम उत्तर

स्कूबा डाइवर्स हीलियम से मिश्रित हवा का उपयोग इसलिए करते हैं क्योंकि हीलियम नाइट्रोजन की तुलना में रक्त और ऊतकों में कम घुलता है। अधिक दबाव पर शरीर में कम inert gas घुलती है और ऊपर आते समय गैस के बुलबुले बनने की संभावना कम हो जाती है। इससे Decompression Sickness या 'Bends' का खतरा कम होता है।

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30 Related MCQs 30 संबंधित बहुविकल्पीय प्रश्न

1. The painful condition commonly known as 'bends' is:

A. Hypothermia

B. Decompression sickness

C. Heat stroke

D. Anaemia

Answer: B. Decompression sickness

2. Which gas mainly causes the bends?

A. Oxygen

B. Hydrogen

C. Nitrogen

D. Helium

Answer: C. Nitrogen

3. Which law explains the increased solubility of nitrogen at high pressure?

A. Boyle's law

B. Charles' law

C. Henry's law

D. Graham's law

Answer: C. Henry's law

4. According to Henry's law, gas solubility is proportional to:

A. Temperature only

B. Partial pressure of gas

C. Volume of container

D. Molecular mass only

Answer: B. Partial pressure of gas

5. At greater underwater depth, pressure:

A. Decreases

B. Remains zero

C. Increases

D. Becomes negative

Answer: C. Increases

6. At high pressure, more nitrogen tends to:

A. Escape from blood

B. Dissolve in tissues

C. React chemically with water

D. Become oxygen

Answer: B. Dissolve in tissues

7. The gas used to replace much of nitrogen in deep-diving mixtures is:

A. Carbon dioxide

B. Helium

C. Chlorine

D. Neon

Answer: B. Helium

8. Helium is preferred because it is relatively:

A. Highly reactive

B. Toxic

C. Inert

D. Combustible

Answer: C. Inert

9. Helium is less soluble in body tissues than:

A. Nitrogen

B. Oxygen

C. Hydrogen

D. Fluorine

Answer: A. Nitrogen

10. Rapid ascent from deep water causes pressure to:

A. Increase rapidly

B. Decrease rapidly

C. Remain constant

D. Become infinite

Answer: B. Decrease rapidly

11. During rapid ascent, dissolved nitrogen may form:

A. Solid particles

B. Gas bubbles

C. Salts

D. Water droplets

Answer: B. Gas bubbles

12. Gas bubbles formed during decompression can:

A. Improve circulation

B. Block blood vessels

C. Increase oxygen production

D. Produce water

Answer: B. Block blood vessels

13. A mixture of helium and oxygen is called:

A. Nitrox

B. Heliox

C. Syngas

D. Producer gas

Answer: B. Heliox

14. Helium has a relatively:

A. High density

B. Low density

C. Very high toxicity

D. High reactivity

Answer: B. Low density

15. Which gas is chemically inert?

A. Helium

B. Oxygen

C. Chlorine

D. Hydrogen

Answer: A. Helium

16. The main gas responsible for nitrogen narcosis is:

A. Nitrogen

B. Helium

C. Oxygen

D. Argon

Answer: A. Nitrogen

17. The solubility of a gas in a liquid generally increases when pressure:

A. Increases

B. Decreases

C. Becomes zero

D. Is irrelevant

Answer: A. Increases

18. Henry's law is related to:

A. Solubility of gases in liquids

B. Atomic radius

C. Ionization energy

D. Chemical equilibrium only

Answer: A. Solubility of gases in liquids

19. The concentration of dissolved gas is represented by:

A. C

B. P only

C. T only

D. V only

Answer: A. C

20. The Henry's law relation can be written as:

A. C = kP

B. PV = nRT

C. E = mc²

D. P = F/A

Answer: A. C = kP

21. Why is pure oxygen not generally used for deep diving?

A. It is always insoluble

B. High oxygen partial pressure can become toxic

C. It has no oxygen atoms

D. It freezes immediately

Answer: B. High oxygen partial pressure can become toxic

22. Helium is classified as a:

A. Noble gas

B. Halogen

C. Alkali metal

D. Chalcogen

Answer: A. Noble gas

23. Helium belongs to:

A. Group 1

B. Group 2

C. Group 17

D. Group 18

Answer: D. Group 18

24. The 'bends' are primarily associated with:

A. Rapid decompression

B. Slow heating

C. Freezing

D. Low humidity

Answer: A. Rapid decompression

25. Which factor determines the amount of gas dissolved according to Henry's law?

A. Partial pressure

B. Atomic number

C. Neutron number

D. Crystal structure

Answer: A. Partial pressure

26. Deep-sea divers experience higher pressure mainly because of:

A. Water column above them

B. Atmospheric heating

C. Sunlight

D. Wind

Answer: A. Water column above them

27. Which mixture may be used for deep diving?

A. Helium + oxygen

B. Chlorine + oxygen

C. Fluorine + oxygen

D. Hydrogen + chlorine

Answer: A. Helium + oxygen

28. The bubbles responsible for decompression sickness are mainly:

A. Nitrogen bubbles

B. Helium crystals

C. Oxygen solids

D. Water bubbles

Answer: A. Nitrogen bubbles

29. Which property of helium makes it useful as a deep-diving gas?

A. High chemical reactivity

B. Low density and low solubility compared with nitrogen

C. High toxicity

D. Ability to burn

Answer: B. Low density and low solubility compared with nitrogen

30. The best explanation for using helium in deep-diving breathing mixtures is:

A. It increases nitrogen absorption

B. It reduces the amount of nitrogen dissolving in tissues

C. It produces oxygen inside the lungs

D. It increases water pressure

Answer: B. It reduces the amount of nitrogen dissolving in tissues

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