JEE Main > Solutions

Explore popular questions from Solutions for JEE Main. This collection covers Solutions previous year JEE Main questions hand picked by popular teachers.


Q 1.    

Correct4

Incorrect-1

Freezing point of an aqueous solution is {tex} ( - 0.186 ) ^ { \circ } \mathrm { C } {/tex} . Elevation of boiling point of the same solution is {tex} K _ { b } = 0.512 ^ { \circ } \mathrm { C } , {/tex} {tex} K _ { f } = 1.86 ^ { \circ } \mathrm { C } , {/tex} find the increase in boiling point.

A

{tex} 0.186 ^ { \circ } \mathrm { C } {/tex}

{tex} 0.0512 ^ { \circ } \mathrm { C } {/tex}

C

{tex} 0.092 ^ { \circ } \mathrm { C } {/tex}

D

{tex} 0.2372 ^ { \circ } \mathrm { C } {/tex}

Explanation





Q 2.    

Correct4

Incorrect-1

In mixture {tex} A {/tex} and {tex} B {/tex} components show -ve deviation as

A

{tex} \Delta V _ { \operatorname { mix } } > 0 {/tex}

B

{tex} \Delta H _ { \operatorname { mix } } < 0 {/tex}

C

{tex} A - B {/tex} interaction is weaker than {tex} A - A {/tex} and {tex} B - B {/tex} interaction

{tex} A - B {/tex} interaction is stronger than {tex} A - A {/tex} and {tex} B - B {/tex} interaction.

Explanation



Q 3.    

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Incorrect-1

If liquids {tex} A {/tex} and {tex} B {/tex} form an ideal solution

A

the entropy of mixing is zero

B

the free energy of mixing is zero

C

the free energy as well as the entropy of mixing are each zero

the enthalpy of mixing is zero

Explanation

Q 4.    

Correct4

Incorrect-1

In a {tex}0.2\, molal {/tex} aqueous solution of a weak acid {tex} HX {/tex} the degree of ionization is {tex} 0.3 {/tex} .Taking {tex} \mathrm { k } _ { \mathrm { f } } {/tex} for water as {tex} 1.85 , {/tex} the freezing point of the solution will be nearest to

A

{tex} - 0.360 ^ { \circ } \mathrm { C } {/tex}

B

{tex} - 0.260 ^ { \circ } \mathrm { C } {/tex}

C

{tex} + 0.480 ^ { \circ } \mathrm { C } {/tex}

{tex} - 0.480 ^ { \circ } \mathrm { C } {/tex}

Explanation



Q 5.    

Correct4

Incorrect-1

A pressure cooker reduces cooking time for food because

boiling point of water involved in cooking is increased

B

the higher pressure inside the cooker crushes the food material

C

cooking involves chemical changes helped by a rise in temperature

D

heat is more evenly distributed in the cooking space

Explanation

Q 6.    

Correct4

Incorrect-1

Which one of the following aqueous solutions will exihibit highest boiling point?

A

{tex} 0.015 \mathrm { M } {/tex} urea

B

{tex}0.01 \mathrm { M }\, KNO _ { 3 } {/tex}

{tex}0.01 \mathrm { M }\, Na_ { 2 } \mathrm { SO } _ { 4 } {/tex}

D

{tex}0.015 \mathrm { \,M } {/tex} glucose

Explanation





Q 7.    

Correct4

Incorrect-1

For which of the following parameters the structural isomers {tex} \mathrm { C } _ { 2 } \mathrm { H } _ { 5 } \mathrm { OH } {/tex} and {tex} \mathrm { CH } _ { 3 } \mathrm { OCH } _ { 3 } {/tex} would be expected to have the same values?(Assume ideal behaviour)

A

Boiling points

B

Vapour pressure at the same temperature

C

Heat of vaporization

Gaseous densities at the same temperature and pressure

Explanation

Q 8.    

Correct4

Incorrect-1

Which of the following liquid pairs shows a positive deviation from Raoult's law?

A

Water - nitric acid

Benzene-methanol

C

Water - hydrochloric acid

D

Acetone - chloroform

Explanation







Q 9.    

Correct4

Incorrect-1

Which one of the following statements is FALSE?

A

The correct order of osmotic pressure for {tex} 0.01\mathrm {\, M } {/tex} aqueous solution of each compound is {tex} \mathrm { BaCl } _ { 2 } > \mathrm { KCl } > \mathrm { CH } _ { 3 } \mathrm { COOH } > sucrose{/tex}

B

The osmotic pressure {tex} ( \pi ) {/tex} of a solution is given by the equation {tex} \pi = \mathrm { MRT } {/tex} , where {tex} M {/tex} is the molarity of the solution

C

Raoult's law states that the vapour pressure of a component over a solution is proportional to its mole fraction

Two sucrose solutions of same molality prepared in different solvents will have the same freezing point depression

Explanation

Q 10.    

Correct4

Incorrect-1

Benzene and toluene form nearly ideal solution. At {tex} 20 ^ { \circ } \mathrm { C } {/tex} , the vapour pressure of benzene is {tex} 75\,torr {/tex} and that of toluene is{tex}\, 22 torr {/tex}. The partial vapour pressure of benzene at {tex} 20 ^ { \circ } \mathrm { C } {/tex} for a solution containing {tex} 78\mathrm { g } {/tex} of benzene and {tex}46 \mathrm { g } {/tex} of toluene in {tex} torr {/tex} is

A

53.5

B

37.5

C

25

50

Explanation





Q 11.    

Correct4

Incorrect-1

Equimolar solutions in the same solvent have

A

Different boiling and different freezing points

B

Same boiling and same freezing points

C

Same freezing point but different boiling points

Same boiling point but different freezing points

Explanation

Q 12.    

Correct4

Incorrect-1

Among the following mixtures, dipole-dipole as the major interaction, is present in

A

{tex} KCl {/tex} and water

B

benzene and carbon tetrachloride

C

benzene and ethanol

acetonitrile and acetone

Explanation





Q 13.    

Correct4

Incorrect-1

{tex}18 \mathrm { g } {/tex} of glucose {tex} \left( \mathrm { C } _ { 6 } \mathrm { H } _ { 12 } \mathrm { O } _ { 6 } \right) {/tex} is added to {tex} 178.2 \mathrm { g } {/tex} of water. The vapour pressure of water for this aqueous solution at {tex} 100 ^ { \circ } \mathrm { C } {/tex} is

A

{tex} 76.00 \,\mathrm { Torr } {/tex}

{tex}752.40\, \mathrm {Torr}{/tex}

C

{tex}759.00\,\mathrm {Torr}{/tex}

D

{tex}7.60\, \mathrm {Torr} {/tex}

Explanation



Q 14.    

Correct4

Incorrect-1

A mixture of ethyl alcohol and propyl alcohol has a vapour pressure of {tex} 290\,\mathrm { mm } {/tex} at {tex}300\, \mathrm { K } {/tex} . The vapour pressure of propyl alcohol is {tex} 200 \,\mathrm { mm } {/tex} . If the mole fraction of ethyl alcohol is {tex} 0.6 {/tex} , its vapour pressure {tex} (in \,\mathrm { mm } ) {/tex} at the same temperature will be

A

360

350

C

300

D

700

Explanation



Q 15.    

Correct4

Incorrect-1

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

A

{tex} 1/2 {/tex}

B

{tex} 2/3 {/tex}

C

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

{tex} 1/3 {/tex}

Explanation







Q 16.    

Correct4

Incorrect-1

A {tex}5.25 \% {/tex} solution of a substance is isotonic with a {tex} 1.5\% {/tex} solution of urea {tex} \left. \text { (molar mass } = 60 \mathrm { g } \mathrm { mol } ^ { - 1 } \right) {/tex} in the same solvent. If the
densities of both the solutions are assumed to be equal to {tex} 1.0\, \mathrm { g } \mathrm { cm } ^ { - 3 } , {/tex} molar mass of the substance will be

{tex} 210.0 \,\mathrm { g } \mathrm { mol } ^ { - 1 } {/tex}

B

{tex}90.0\, \mathrm { g } \mathrm { mol } ^ { - 1 } {/tex}

C

{tex}115.0\, \mathrm { g } \mathrm { mol } ^ { - 1 } {/tex}

D

{tex}105.0\, \mathrm { g } \mathrm { mol } ^ { - 1 } {/tex}

Explanation







Q 17.    

Correct4

Incorrect-1

At {tex} 80 ^ { \circ } \mathrm { C } {/tex} , the vapour pressure of pure liquid {tex} { 'A' } {/tex} is {tex} 520\,\mathrm { mm } {/tex} {tex} Hg {/tex} and that of pure liquid {tex} {' B '} {/tex} ' is {tex} 1000\,\mathrm { mm } {/tex} {tex} Hg {/tex}. If a mixture solution of {tex} { 'A' } {/tex} and {tex} {' B '} {/tex} boils at {tex} 80 ^ { \circ } \mathrm { C } {/tex} and {tex}1\, \mathrm atm {/tex} pressure, the amount of {tex} {' A '} {/tex} in the mixture is {tex} ( 1 \mathrm { atm } = 760 \mathrm { mm }\, \mathrm { Hg } ) {/tex}

A

{tex}52\, \mathrm {mol}{/tex} percent

B

{tex}34\, \mathrm {mol} {/tex} percent

C

{tex}48\, \mathrm {mol}{/tex} percent

{tex}50\, \mathrm {mol}{/tex} percent

Explanation







Q 18.    

Correct4

Incorrect-1

The vapour pressure of water at {tex} 20 ^ { \circ } \mathrm { C } {/tex} is {tex} 17.5\mathrm { mm } {/tex} Hg. If {tex}18 \mathrm { g } {/tex} of glucose {tex} \left( \mathrm { C } _ { 6 } \mathrm { H } _ { 12 } \mathrm { O } _ { 6 } \right) {/tex} is added to {tex}178.2 \mathrm { g } {/tex} of water at {tex} 20 ^ { \circ } \mathrm { C } , {/tex} the vapour pressure of the resulting solution will be

{tex}17.325\, \mathrm { mm }\, \mathrm { Hg } {/tex}

B

{tex}15.750\, \mathrm { mm } \,\mathrm { Hg } {/tex}

C

{tex} 16.500\,\mathrm { mm } \, \mathrm { Hg } {/tex}

D

{tex}17.500\, \mathrm { mm } \,\mathrm { Hg } {/tex}

Explanation







Q 19.    

Correct4

Incorrect-1

A binary liquid solution is prepared by mixing {tex} n-heptane {/tex} and ethanol. Which one of the following statements is correct regarding the behaviour of the solution?

A

The solution is non-ideal, showing -ve deviation from Raoult's Law.

The solution is non-ideal, showing +ve deviation from Raoult's Law.

C

n-heptane shows +ve deviation while ethanol shows -ve deviation from Raoult's Law.

D

The solution formed is an ideal solution.

Explanation

Q 20.    

Correct4

Incorrect-1

Two liquids {tex} X {/tex} and {tex} Y {/tex} form an ideal solution. At {tex} 300\,\mathrm { K } {/tex} , vapour pressure of the solution containing {tex} 1\mathrm { mol } {/tex} of {tex} X {/tex} and 3{tex} \mathrm { mol } {/tex} of {tex} Y {/tex} is {tex}550\, \mathrm { mm } \mathrm { Hg } {/tex} . At the same temperature, if {tex}1 \mathrm { mol } {/tex} of {tex} Y {/tex} is further added to this solution, vapour pressure of the solution increases by {tex}10\, \mathrm { mm }\, \mathrm { Hg }{/tex}. Vapour pressure {tex} \text { (in } \mathrm { mm } \mathrm { Hg } ) {/tex} of {tex} X {/tex} and {tex} Y {/tex} in their pure states will be, respectively:

A

300 and 400

400 and 600

C

500 and 600

D

200 and 300

Explanation


Q 21.    

Correct4

Incorrect-1

If sodium sulphate is considered to be completely dissociated into cations and anions in aqueous solution, the change in freezing point of water {tex} \left( \Delta T _ { f } \right) , {/tex} when {tex} 0.01\,\mathrm { mol } {/tex} of sodium sulphate is dissolved in {tex}1\, \mathrm { kg } {/tex} of water, is {tex} \left( K _ { f } = 1.86 \mathrm { K }\, \mathrm { kg } \mathrm { mol } ^ { - 1 } \right) {/tex}

A

{tex} 0.372\, \mathrm { K } {/tex}

{tex}0.0558\, \mathrm { K } {/tex}

C

{tex}0.0744\, \mathrm { K } {/tex}

D

{tex}0.0186\, \mathrm { K } {/tex}

Explanation



Q 22.    

Correct4

Incorrect-1

On mixing, heptane and octane form an ideal solution. At {tex}373\, \mathrm { K } {/tex} , the vapour pressures of the two liquid components (heptane and octane) are {tex}105\, \mathrm { kPa } {/tex} and {tex} 45\, \mathrm { kPa } {/tex} respectively. Vapour pressure of the solution obtained by mixing {tex}25.0\,\mathrm { g } {/tex} of heptane and {tex}35\, \mathrm { g } {/tex} of octane will be
(molar mass of heptane {tex} = 100 \mathrm { g } \mathrm { mol } ^ { - 1 } {/tex} and of octane {tex} = 114 \mathrm { g } {/tex} {tex} \mathrm { mol } ^ { - 1 } {/tex})

{tex}72.0\, \mathrm { kPa } {/tex}

B

{tex}36.1\, \mathrm { kPa } {/tex}

C

{tex}96.2\, \mathrm { kPa } {/tex}

D

{tex}144.5\, \mathrm { kPa } {/tex}

Explanation







Q 23.    

Correct4

Incorrect-1

A 5.2 molal aqueous solution of methyl alcohol, {tex} \mathrm { CH } _ { 3 } \mathrm { OH } , {/tex} is supplied. What is the mole fraction of methyl alcohol in the solution?

A

0.100

B

0.190

0.086

D

0.050

Explanation





Q 24.    

Correct4

Incorrect-1

Ethylene glycol is used as an antifreeze in a cold climate. Mass of ethylene glycol which should be added to {tex}4\, \mathrm { kg } {/tex} of water to prevent it from freezing at {tex} - 6 ^ { \circ } \mathrm { C } {/tex} will be : {tex} \left( \mathrm { K } _ { \mathrm { f } } \text { } \right. {/tex}for water {tex} = 1.86 \mathrm { K } \mathrm { kg } \mathrm { mol } ^ { - 1 } {/tex} , and molar mass of ethylene glycol {tex} \left. = 62 \mathrm { g } \mathrm { mol } ^ { - 1 } \right) {/tex}

{tex}804.32\, \mathrm { g } {/tex}

B

{tex}204.30\, \mathrm { g } {/tex}

C

{tex}400.00\, \mathrm { g } {/tex}

D

{tex}304.60\, \mathrm { g } {/tex}

Explanation





Q 25.    

Correct4

Incorrect-1

The degree of dissociation {tex} ( \alpha ) {/tex} of a weak electrolyte, {tex} \mathrm { A } _ { \mathrm { x } } \mathrm { B } _ { \mathrm { y } } {/tex} is related to van't Hoff factor (i) by the expression

{tex} \alpha = \frac { i - 1 } { ( x + y - 1 ) } {/tex}

B

{tex} \alpha = \frac { i - 1 } { x + y + 1 } {/tex}

C

{tex} \alpha = \frac { x + y - 1 } { i - 1 } {/tex}

D

{tex} \alpha = \frac { x + y + 1 } { i - 1 } {/tex}

Explanation