Explore popular questions from Equilibrium for JEE Advanced. This collection covers Equilibrium previous year JEE Advanced questions hand picked by experienced teachers.

## Chemistry

Equilibrium

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Q 1. The oxidation of {tex} \mathrm { SO } _ { 2 } {/tex} by {tex} \mathrm { O } _ { 2 } {/tex} to {tex} \mathrm { SO } _ { 3 } {/tex} is an exothermic reaction. The yield of {tex} \mathrm { SO } _ { 3 } {/tex} will be maximum if

A

temperature is increased and pressure is kept constant

temperature is reduced and pressure is increased

C

both temperature and pressure are increased

D

both temperature and pressure are reduced

##### Explanation

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Q 2. For the reaction {tex} \mathrm { H } _ { 2 } ( \mathrm { g } ) + \mathrm { I } _ { 2 } ( \mathrm { g } ) \rightleftharpoons 2 \mathrm { HI } ( \mathrm { g } ) , {/tex} the equilibrium constant {tex} K _ { p } {/tex} changes with

A

total pressure

B

catalyst

C

the amounts of {tex} \mathrm { H } _ { 2 } {/tex} and {tex} \mathrm { I } _ { 2 } {/tex} present

temperature

##### Explanation

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Q 3. One mole of {tex} \mathrm { N } _ { 2 } \mathrm { O } _ { 4 } ( \mathrm { g } ) {/tex} at {tex} 300 \mathrm { K } {/tex} is kept in a closed container under one atmosphere. It is heated to {tex} 600 \mathrm { K } {/tex} when {tex} 20 \% {/tex} by mass of {tex} \mathrm { N } _ { 2 } \mathrm { O } _ { 4 } ( \mathrm { g } ) {/tex} decomposes to {tex} \mathrm { NO } _ { 2 } ( \mathrm { g } ) {/tex}. The resultant pressure is

A

1.2 atm

2.4atm

C

2.0 atm

D

1.0 atm

##### Explanation

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Q 4. Haber-Bosch process for the manufacture of {tex} \mathrm { NH } _ { 3 } {/tex} is based on the reaction
{tex} \mathrm { N } _ { 2 } ( \mathrm { g } ) + 3 \mathrm { H } _ { 2 } ( \mathrm { g } ) \stackrel { \text { catalyst } } { \rightleftharpoons } 2 \mathrm { NH } _ { 3 } ( \mathrm { g } ) ; \quad \Delta _ { \mathrm { r } } H ^ { \circ } = - 45.0 \mathrm { kJ } \mathrm { mol } ^ { - 1 } ; K _ { p } ^ { \circ } = 14 {/tex}
Which of the following information regarding the above reaction is correct?

A

On adding {tex} \mathrm { N } _ { 2 } , {/tex} the equilibrium is shifted to right side with an increase in entropy.

B

The equilibrium constant {tex} K _ { p } ^ { \circ } {/tex} increases with increase in temperature.

At equilibrium, {tex} 2 G _ { \mathrm { m } } \left( \mathrm { NH } _ { 3 } \right) = G _ { \mathrm { m }} ( \mathrm { N_2 } ) + 3 G _ { \mathrm { m } } \left( \mathrm { H } _ { 2 } \right) {/tex} where {tex} G _ { \mathrm { m } } {/tex} represents the molar Gibbs function of the species enclosed within the brackets.

D

The use of catalyst helps increasing the rate of forward reaction more than that of backward reaction thereby increasing the yield of {tex} \mathrm { NH } _ { 3 } {/tex}.

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Q 5. The {tex} \% {/tex} yield of ammonia as a function of time in the reaction {tex} \mathrm { N } _ { 2 } ( \mathrm { g } ) + 3 \mathrm { H } _ { 2 } ( \mathrm { g } ) \rightleftharpoons 2 \mathrm { NH } _ { 3 } ( \mathrm { g } ) ; \Delta H < 0 {/tex} at {tex} \left( P , T _ { 1 } \right) {/tex} is given below:

If this reaction is conducted at {tex} \left( P , T _ { 2 } \right) , {/tex} with {tex} T _ { 2 } /> T _ { 1 } , {/tex} the {tex} \% {/tex} yield of ammonia as a function of time is represented by

A

B

D

##### Explanation

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Q 6.

A solution which is is treated with M sulphide ion. If

respectively, which one will

precipitate first?

A

B

D

##### Explanation

On the basis of precipitation concept an electrolyte will be precipitated firstly whose ionic product is exceeded to its solubility product. In similar ionic conc. of cations, an electrolyte is precipitated firstly for which is lower. In these electrolytes is precipitated firstly.

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Q 7.

Which of the following salts will not undergo hydrolysis in water?

Sodium sulphate

B

Ammonium sulphate

C

Aluminium sulphate

D

All the salts will hydrolyse

##### Explanation

Salt of do not undergo hydrolysis. So is a salt of

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Q 8.

of is . At what minimum pH, ions starts precipitating 0.01

A

B

D

##### Explanation

Precipitation starts when

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Q 9.

For the reversible reaction

at , the value of is when the partial pressure is measured in atmosphere. The corresponding value of with concentration in mal is

A

B

C

##### Explanation

or

or

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Q 10.

For the system the equilibrium concentration is

The for the reaction is

250

B

416

C

D

125

##### Explanation

At

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Q 11.

The pH of a dilute solution of acetic acid was found to be 4.3. The addition of a small crystal of sodium acetate will cause pH to

A

Becomes less than 4.3

Become more than 4.3

C

Remain equal to 4.3

D

Unpredictable

##### Explanation

Due to common ion , the suppression of ionization of takes place, so the concentration of decreases, so pH increases. So pH must be more than 4.3

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Q 12.

The pH of a solution of weak base at neutralization with strong acid is 8. for the base is

A

C

D

None of there

##### Explanation

At half neutralization,

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Q 13.

Auto-ionisation of liquid is

With at

Number of amide ions present per of pure liquid is

602

B

301

C

200

D

100

##### Explanation

of solution contains molecules of

of solution contains

ions

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Q 14.

1 mol of is mixed with 3 mol of in a litre container. If 50% of is converted into ammonia by the reaction , then the total number of

moles of gas at the equilibrium are

A

1.5

B

4.5

3

D

6

##### Explanation

Total moles

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Q 15.

pH signifies:

Puissance de hydrogen

B

C

All the above

D

##### Explanation

pH stands for Fench word puissance de hydrogen which means power of hydrogen ions

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Q 16.

The of acetyl salicylic acid (aspirin) is 3.5. The pH of gastric juice in human stomach is about 2-3 and the pH in the same intestine is about 8. Aspirin will be

A

Unionized in the small intestine and in the stomach

B

Completely ionsed in the small intestine and in the stomach

C

Ionized in the stomach and almost unionized in the small intestine

Ionized in small intestine and almost unionized in the stomach

##### Explanation

Aspirin is a weak acid ad its ionization is suppressed due to common ion effect in acidic medium, i.e., in stomach. Therefore, aspirin is unionized in stomach whereas in small intestine its pH is basic. So the ionization of aspirin increases, that is why it is completely ionized in small intestine

combines and aspirin forms sodium salt

Therefore, ionization of aspirin increases

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Q 17.

Passing gas into a mixture of ions in an acidified aqueous solution precipitates

CuS and HgS

B

MnS and CuS

C

MnS and NiS

D

NiS and HgS

##### Explanation

In acidic medium, is very feebly ionised giving very small concentration of sulphide ion for precipitation. Therefore, the most insoluble salts are precipitated only.

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Q 18.

In the formation of nitric acid, and are made to combine. Thus, + Heat which of the following condition will favour the formation of ?

A

Low temperature

High temperature

C

Freezing point

D

All are favourable

##### Explanation

The above equation shows that the reaction is endothermic. Endothermic reactions are forward in forward direction at high temperature

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Q 19.

The decomposition of to is carried out at in chloroform. When equilibrium is reached, of and of are present in a 2L solution. The equilibrium constant for the reaction

is

A

B

D

##### Explanation

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Q 20.

Solubility of salt is , its solubility product is

A

B

C

##### Explanation

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Q 21.

In 1L saturated solution of , 0.1 mole of is added. The resultant concentration of Ag in the solution is . The value of is

A

3

B

5

7

D

9

##### Explanation

It is a case of simultaneous solubility of salts with a common ion. Here solubility product of is much greater than that of , it can be assumed that in solution comes mainly from .

Now for

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Q 22.

The conjugate acid of is

B

C

D

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Q 23.

In alkaline solution, the following equilibrium exist
a. equilibrium constant

b. equilibrium constant

and have values 12 and 11, respectively?

What is equilibrium constant for the reaction

A

132

C

1.09

D

0.918

##### Explanation

i.

ii.

The equation constant for the reaction,

iii.

Since eq. (iii) is obtained by reversing and adding equations (i) and (ii)

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Q 24.

If ammonia is added to pure water, the concentration of a chemical species already present will decrease. The species is

A

B

D

##### Explanation

Due to common ion , the self ionization of is suppressed so the concentration of is decreased

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Q 25.

The equilibrium constant for a reaction

is at and is at

The chemical process resulting in the formation of C and D is

A

Exothermic

Endothermic

C

Unpredictable

D

None

##### Explanation

Since increases on increasing temperature, so the reaction will go forward by increasing temperature and hence is endothermic