Statement (S): The dissociation constant of water at $60^{\circ} \mathrm{C}$ is $10^{-13}$. Explanation (E): The $\mathrm{pH}$ of water is 6.5 and that it behaves as acid at $60^{\circ} \mathrm{C}$.

Both S and E are correct and E is correct explanation for S

Both S and E are correct but E is not correct explanation for S

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JEE • CHEMISTRY • Equilibrium

Equilibrium practice · Medium

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Practice format and chapter quiz

These sets use single-correct-answer MCQs. They do not cover every JEE Main or JEE Advanced question format and are not full-length mock papers.

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Showing 391-401 of 401 questions

391 Medium

391 of 401

Application +4 | -1

4.0

moles of argon and

5.0

moles of

\mathrm{PCl}_5

are introduced into an evacuated flask of 100 litre capacity at

610 \mathrm{~K}

. The system is allowed to equilibrate. At equilibrium, the total pressure of mixture was found to be

6.0 \mathrm{~atm}

. The

\mathrm{K}_p

for the reaction is [Given :

R=0.082 \mathrm{~L}

atm

\mathrm{K}^{-1} \mathrm{~mol}^{-1}

]

View answer and explanation

Correct option: A

2.25

Option A (2.25) is correct because it involves calculating the equilibrium constant Kp based on the partial pressures of the reactants and products at equilibrium.

392 Medium

392 of 401

Analyzing +4 | -1

Which of the following will occur if a

0.1 \mathrm{~M}

solution of a weak acid is diluted to

0.01 \mathrm{~M}

at constant temperature?

View answer and explanation

Correct option: C

Percentage ionization will increase

Option C (Percentage ionization will increase) is correct because, according to Ostwald's dilution law, the degree of ionization of a weak acid increases upon dilution.

393 Medium

393 of 401

Analyzing +4 | -1

Assertion (A):

\mathrm{N}_2 \mathrm{O}_4(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NO}_2(\mathrm{~g})

is the example of homogeneous equilibrium.

Reason (R): For this reaction,

\mathrm{K}_{\mathrm{c}}

has unit

\mathrm{L}

\mathrm{mol}

and

\mathrm{K}_{\mathrm{p}}

has unit bar.

View answer and explanation

Correct option: C

Assertion is true and Reason is false

Option C (Assertion is true and Reason is false) is correct because the reaction is indeed a homogeneous equilibrium, but the units for

K_c

and

K_p

are incorrect.

394 Medium

394 of 401

Understanding +4 | -1

A reversible reaction is one which

View answer and explanation

Correct option: B

Proceeds in both directions

Option A (Prevent the hydrolysis of ferrous sulphate) is correct because ferrous ions undergo hydrolysis in water, and adding dilute sulfuric acid prevents this.

395 Medium

395 of 401

Understanding +4 | -1

In which reaction ammonia acts as an acid?

View answer and explanation

Correct option: C

\mathrm{N}{\mathrm{H}_3} + \mathrm{Na} \to \mathrm{NaN}{\mathrm{H}_2} + \frac{1}{2}{\mathrm{H}_2}

Option C (

\mathrm{N}{\mathrm{H}_3} + \mathrm{Na} \to \mathrm{NaN}{\mathrm{H}_2} + \frac{1}{2}{\mathrm{H}_2}

) is correct because ammonia donates a proton (H⁺) to sodium, acting as an acid.

396 Medium

396 of 401

Analyzing +4 | -1

Assertion :- When an acid or a base is added to water at constant temperature the pH changes.

Reason :- This is due to change in ionic product of water.

View answer and explanation

Correct option: C

If Assertion is True but the Reason is False

Option C (If Assertion is True but the Reason is False) is correct because adding an acid or base changes pH, but not due to a change in the ionic product of water (Kw).

397 Medium

397 of 401

Application +4 | -1

If the

\mathrm{pH}

value is 4.5 for a solution then what is the value of

\mathrm{H}^{+}

concentration ?

View answer and explanation

Correct option: A

3.162 \times 10^{-5} \mathrm{~mol} / \mathrm{L}

Option A (

3.162 \times 10^{-5} \mathrm{~mol} / \mathrm{L}

) is correct because it is the result of calculating the hydrogen ion concentration using the formula

[H^+] = 10^{-pH}

398 Medium

398 of 401

Understanding +4 | -1

Assertion (A): When the concentration of any of the reactants or products in a reaction at equilibrium is changed, the composition of the equilibrium mixture changes, so as to minimize the effect of concentration changes.

Reason (R): It illustrates Le-Chatelier's principle on the effect of concentration change.

View answer and explanation

Correct option: A

Both Assertion and Reason are true and Reason is the correct explanation for Assertion

Option A (Both Assertion and Reason are true and Reason is the correct explanation for Assertion) is correct because Le Chatelier's principle states that if a change of condition is applied to a system in equilibrium, the system will shift in a direction that relieves the stress, and changing the concentration of reactants or products is a stress.

399 Medium

399 of 401

Application +4 | -1

In a closed tube,

\mathrm{HI}(\mathrm{g})

is heated at

440^{\circ} \mathrm{C}

up to establishment of equilibrium. If it dissociates into

\mathrm{H}_2(\mathrm{g})

and

\mathrm{I}_2(\mathrm{g})

up to

22 \%,

then the dissociation constant is

View answer and explanation

Correct option: C

0.0199

Option C (0.0199) is correct because the dissociation constant K is calculated based on the equilibrium concentrations of HI, H₂, and I₂.

400 Medium

400 of 401

Analyzing +4 | -1

Statement (S): The dissociation constant of water at

60^{\circ} \mathrm{C}

10^{-13}

.

Explanation (E): The

\mathrm{pH}

of water is 6.5 and that it behaves as acid at

60^{\circ} \mathrm{C}

View answer and explanation

Correct option: A

S is correct but E is wrong

Option A (S is correct but E is wrong) is correct because while the dissociation constant of water at 60°C is indeed around

10^{-13}

, the pH of 6.5 at that temperature still indicates neutrality, not acidity.

401 Medium

401 of 401

Application +4 | -1

For the equilibrium

A B_{3(\mathrm{g})} \rightleftharpoons 1 / 2 A_{2(\mathrm{g})}+3 / 2 B_{2(\mathrm{g})},

the value of the equilibrium constant is

3.0 \times 10^{-6}

at 1000 K. Find

\mathrm{K}_{\mathrm{p}}

for the reaction at this temperature (given

\mathrm{R}: 8.314 \mathrm{~JK}^{-1} \mathrm{~mol}^{-1})

View answer and explanation

Correct option: B

2.494 \times 10^{-2}

Option B (

2.494 \times 10^{-2}

) is correct because it is calculated using the relationship between Kp and Kc, considering the change in the number of moles.

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