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JEE Main

Explore popular questions from States of Matter: Gases and Liquids for JEE Main. This collection covers States of Matter: Gases and Liquids previous year JEE Main questions hand picked by experienced teachers.

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States of Matter: Gases and Liquids

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Q 1. Density of a gas is found to be {tex}5.46 \mathrm { g } / \mathrm { dm } ^ { 3 } {/tex} at {tex} 27 ^ { \circ } \mathrm { C } {/tex} at {tex}\mathrm{2 \ bar}{/tex} pressure. What will be its density at STP?

A

6{tex} \mathrm { gm } / 1 {/tex}

B

8{tex} \mathrm { gm } / 1 {/tex}

3{tex} \mathrm { gm } / 1 {/tex}

D

1.5{tex} \mathrm { gm } /l {/tex}

Explanation


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Q 2. Calculate the temperature of 4.0 mole of a gas occupying 5{tex} \mathrm { dm } ^ { 3 } {/tex} at 3.32 bar. {tex} \left( \mathrm { R } = 0.83 \text { bar } \mathrm { dm } ^ { 3 } \mathrm { K } ^ { - 1 } \mathrm { mol } ^ { - 1 } \text { ) } \right. {/tex}

A

100{tex} \mathrm { K } {/tex}

50{tex} \mathrm { K } {/tex}

C

150{tex} \mathrm { K } {/tex}

D

200{tex} \mathrm { K } {/tex}

Explanation

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Q 3. Calculate the volume occupied by {tex} 8.8\mathrm { g } {/tex} of {tex} \mathrm { CO } _ { 2 } {/tex} at {tex} 31.1 ^ { \circ } \mathrm { C } {/tex} and 1 bar pressure. {tex}\mathrm R = 0.083 \mathrm { bar } \mathrm { LK } ^ { - 1 } \mathrm { mol } ^ { - 1 } {/tex} .

A

10.10{tex} \mathrm { ltr } {/tex}

B

8.05{tex} \mathrm { ltr } {/tex}

C

2.01{tex} \mathrm { ltr } {/tex}

5.05{tex} \mathrm { ltr } {/tex}

Explanation

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Q 4. {tex} 380\mathrm { mL } {/tex} of a gas at {tex} 27 ^ { \circ } \mathrm { C } , 800 \mathrm { mm } {/tex} of {tex}\mathrm{Hg}{/tex} weights {tex}0.455 \mathrm { g } . {/tex} The molecular weight of gas is

A

27

28

C

29

D

30

Explanation

The standard way to do this problem is to use the gas law equation: PV = nRT P = pressure = 800/760 = 1.053 atm V = volume = 0.380L n = number of moles R = gas law constant = 0.082057 T = temp in K = 27+273 = 300 Substitute: 1.053* 0.380 = n * 0.082057*300 n = ( 1.053*0.380) / ( 0.082057*300) n = 0.400/ 24.6171 n = 0.0162 mol 0.455g = 0.0162 mol 1mol = 0.455/ 0.0162 = 28.00g/mol

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Q 5. What is the ratio of the rate of diffusion of {tex} \mathrm { O } _ { 2 } {/tex} and {tex} \mathrm { H } _ { 2 } {/tex} at same {tex} \mathrm P {/tex} and {tex} \mathrm T ? {/tex}

{tex} 1 : 4 {/tex}

B

{tex} 1 : 8 {/tex}

C

{tex} 1 : 16 {/tex}

D

{tex} 4 : 1 {/tex}

Explanation

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Q 6. Equal weights of methane and oxygen are mixed in an empty container at {tex} 25 ^ { \circ } \mathrm { C } {/tex} . What is the fraction of the total pressure exerted by oxygen?

{tex} \frac { 1 } { 3 } {/tex}

B

{tex} \frac { 1 } { 2 } {/tex}

C

{tex} \frac { 2 } { 3 } {/tex}

D

{tex} \frac { 1 } { 3 } \times \frac { 273 } { 298 } {/tex}

Explanation

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Q 7. Calculate the total pressure in a mixture of {tex} 8\mathrm { g } {/tex} of dioxygen and {tex} 4\mathrm { g } {/tex} of dihydrogen confined in a vessel of {tex}1 \mathrm { dm } ^ { 3 } {/tex} at {tex} 27 ^ { \circ } \mathrm { C } .\mathrm R = 0.083 \, \mathrm { bar }\, \mathrm { dm } ^ { 3 } \mathrm { K } ^ { - 1 } \mathrm { mol } ^ { - 1 } . {/tex}

A

28.5 bar

56.025 bar

C

112.5 bar

D

14.25 bar

Explanation

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Q 8. A sample of gas at {tex} 35 ^ { \circ } \mathrm { C } {/tex} and {tex}\mathrm{1 \ atm}{/tex}pressure occupies a volume of {tex}\mathrm{3.75 \ ltr.}{/tex} At what temperature should the gas be kept if it is required to reduce the volume to {tex}\mathrm{3 \ ltr.}{/tex} at the same pressure?

{tex} - 26.6 ^ { \circ } \mathrm { C } {/tex}

B

{tex} 0 ^ { \circ } \mathrm { C } {/tex}

C

{tex} 3.98 ^ { \circ } \mathrm { C } {/tex}

D

{tex} 28 ^ { \circ } \mathrm { C } {/tex}

Explanation

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Q 9. The average speed of an ideal gas molecule at {tex} 27 ^ { \circ } \mathrm { C } {/tex} is {tex}0.3 \mathrm { m } \mathrm{sec^{-1}} {/tex} . The average speed at {tex} 927 ^ { \circ } \mathrm { C } {/tex} is

A

0.15{tex} \mathrm { m } \mathrm { sec } ^ { - 1 } {/tex}

0.6{tex} \mathrm { m } \mathrm { sec } ^ { - 1 } {/tex}

C

1.2{tex} \mathrm { m } \mathrm { sec } ^ { - 1 } {/tex}

D

0.6{tex} \mathrm { cm } \mathrm { sec } ^ { - 1 } {/tex}

Explanation

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Q 10. In van der Waals equation of state of the gas law, the constant {tex}'b'{/tex} is a measure of

volume occupied by the molecules

B

intermolecular attraction

C

intermolecular repulsions

D

intermolecular collisions per unit volume

Explanation

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Q 11. The compressibility factor for a real gas at high pressure is

A

{tex} 1 + \frac { R T } { p b } {/tex}

B

{tex}1{/tex}

{tex} 1 + \frac { p b } { R T } {/tex}

D

{tex} 1 - \frac { p b } { R T } {/tex}

Explanation



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Q 12. As the temperature is raised from {tex} 20 ^ { \circ } \mathrm { C } {/tex} to {tex} 40 ^ { \circ } \mathrm { C } {/tex} , the average kinetic energy of neon atoms changes by a factor of which of the following?

{tex} \frac { 313 } { 293 } {/tex}

B

{tex} \sqrt { ( 313 / 293 ) } {/tex}

C

{tex} \frac { 1 } { 2 } {/tex}

D

{tex}2{/tex}

Explanation

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Q 13. Na and Mg crystallize in {tex} b c c {/tex} and {tex} f c c {/tex} type crystals respectively, then the number of atoms of Na and Mg present in the unit cell of their respective crystal is

A

4 and 2

B

9 and 14

C

14 and 9

2 and 4

Explanation


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Q 14. Kinetic theory of gases proves

A

only Boyle's law

B

only Charles' law

C

only Avogadro's law

All of these.

Explanation

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Q 15. The ratio of masses of oxygen and nitrogen in a particular gaseous mixture is {tex} 1 : 4 . {/tex} The ratio of number of their molecule is:

A

{tex} 1 : 4 {/tex}

B

{tex} 7 : 32 {/tex}

{tex} 1 : 8 {/tex}

D

{tex} 3 : 16 {/tex}

Explanation

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Q 16. What type of crystal defect is indicated in the diagram below?
{tex} \mathrm { Na } ^ { + } \mathrm { Cl } ^ { - } \mathrm { Na } ^ { + } \mathrm { Cl } ^ { - } \mathrm { Na } ^ { + } \mathrm { Cl } ^ { - } {/tex}
{tex} \mathrm { Cl } ^ { - } \square \mathrm { Cl } ^ { - } \mathrm { Na } ^ { + } \square \mathrm { Na } ^ { + } {/tex}
{tex} \mathrm { Na } ^ { + } \mathrm { Cl } ^ { - } \square \mathrm { Cl } ^ { - } \mathrm { Na } ^ { + } \mathrm { Cl } ^ { - } {/tex}
{tex} \mathrm { Cl } ^ { - } \mathrm { Na } ^ { + } \mathrm { Cl } ^ { - } \mathrm { Na } ^ { + } \square \mathrm { Na } ^ { + } {/tex}

A

Frenkel defect

Schottky defect

C

interstitial defect

D

Frenkel and Schottky defects.

Explanation


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Q 17. For an ideal gas, number of moles per litre in terms of its pressure {tex} \mathrm P {/tex}, gas constant {tex} \mathrm R {/tex} and temperature {tex}\mathrm T {/tex} is

A

{tex}\mathrm {P T / R} {/tex}

B

{tex} \mathrm {PRT} {/tex}

{tex} \mathrm {P / R T} {/tex}

D

{tex}\mathrm {R T / P} {/tex}.

Explanation

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Q 18. If {tex} 10 ^ { - 4 } \mathrm { dm } ^ { 3 } {/tex} of water is introduced into a {tex} 1.0 \mathrm { dm } ^ { 3 } {/tex} flask at {tex} 300 \mathrm { K } , {/tex} how many moles of water are in the vapour phase when equilibrium is established?
(Given : Vapour pressure of {tex} \mathrm { H } _ { 2 } \mathrm { O } {/tex} at {tex} 300 \mathrm { K } {/tex} is {tex}3170 \mathrm { Pa } {/tex} ; {tex} \left. R = 8.314 \mathrm { JK } ^ { - 1 } \mathrm { mol } ^ { - 1 } \right) {/tex}

A

{tex} 5.56 \times 10 ^ { - 3 } \mathrm { mol } {/tex}

B

{tex} 1.53 \times 10 ^ { - 2 } \mathrm { mol } {/tex}

C

{tex} 4.46 \times 10 ^ { - 2 } \mathrm { mol } {/tex}

{tex} 1.27 \times 10 ^ { - 3 } \mathrm { mol } {/tex}

Explanation

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Q 19. Which one of the following statements is not true about the effect of an increase in temperature on the distribution of molecular speeds in a gas?

A

The most probable speed increases.

The fraction of the molecules with the most probable speed increases.

C

The distribution becomes broader.

D

The area under the distribution curve remains the same as under the lower temperature.

Explanation



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Q 20. The average kinetic energy associated with one mole of a gas is

{tex} \frac { 3 } { 2 } \mathrm { RT } {/tex}

B

{tex} \frac { 3 } { 2 } \mathrm { KT } {/tex}

C

{tex} \frac { 1 } { 2 } \mathrm { RT } {/tex}

D

{tex} \frac { 1 } { 2 } \mathrm { KT } {/tex}

Explanation

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Q 21. {tex}0.2 {/tex}g of a gas {tex} \mathrm { X } {/tex} occupies a volume of {tex}0.44{/tex} litre at given pressure and temperature. Under identical conditions of {tex} \mathrm { P } {/tex} and {tex} \mathrm { T } , 0.1 \mathrm { g } {/tex} of {tex} \mathrm { CO } _ { 2 } {/tex} gas occupies {tex} 0.32 \mathrm { L } {/tex} volume. The gas {tex} \mathrm { X } {/tex} can be

A

{tex} \mathrm {O _ { 2 }} {/tex}

{tex} \mathrm { SO } _ { 2 } {/tex}

C

{tex} \mathrm { NO } {/tex}

D

{tex} \mathrm { C } _ { 4 } \mathrm { H } _ { 10 } {/tex}

Explanation

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Q 22. A sample of gas at constant temperature occupies {tex} 95 \mathrm { cm } ^ { 3 } {/tex} under a pressure of {tex} 9.962 \times 10 ^ { 4 } \mathrm { N } / \mathrm { m } ^ { 2 } {/tex}. At the same temperature, its volume at a pressure of {tex} 10.13 \times 10 ^ { 4 } \mathrm { N } / \mathrm { m } ^ { 2 } {/tex} is

A

{tex} 190 \mathrm { cm } ^ { 3 } {/tex}

{tex} 93 \mathrm { cm } ^ { 3 } {/tex}

C

{tex} 46.5 \mathrm { cm } ^ { 3 } {/tex}

D

{tex} 47.5 \mathrm { cm } ^ { 3 } {/tex}

Explanation

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Q 23. Which of the following statements is incorrect?

A

At {tex} 273 ^ { \circ } \mathrm { C } {/tex} and {tex} 1 \mathrm { atm } {/tex} pressure the volume of a given mass of gas will be twice the volume at {tex} 0 ^ { \circ } \mathrm { C } {/tex} and {tex} 1 \mathrm { atm } {/tex} pressure

B

At {tex} - 136.5 ^ { \circ } \mathrm { C } {/tex} and {tex} 1 \mathrm { atm } {/tex} pressure, the volume of a given mass of gas will be half its volume at {tex} 0 ^ { \circ } \mathrm { C } {/tex} and {tex} 1 \mathrm { atm } {/tex}

C

The mass ratio of equal volumes of {tex} \mathrm { NH } _ { 3 } {/tex} and {tex} \mathrm { H } _ { 2 } \mathrm { S } {/tex} under similar conditions of temperature and pressure is 1: 2

The molar ratio of equal masses of {tex} \mathrm { CH } _ { 4 } {/tex} and {tex} \mathrm { SO } _ { 2 } {/tex} is 1: 4

Explanation

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Q 24. At what temperature, the average speed of gas molecules will be double that at {tex} 27 ^ { \circ } \mathrm { C } ? {/tex}

A

{tex} 27 ^ { \circ } \mathrm { C } {/tex}

B

{tex} 327 ^ { \circ } \mathrm { C } {/tex}

C

{tex} 527 ^ { \circ } \mathrm { C } {/tex}

{tex} 927 ^ { \circ } \mathrm { C } {/tex}

Explanation

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Q 25. Which of the following graphs represent Boyle's law correctly? ( {tex} \mathrm { n } _ { 1 } {/tex} and {tex} \mathrm { n } _ { 2 } {/tex} are number of moles)

A

B

D

Explanation