Ncert Exercises & Solutions

Given below are two statements:

Assertion (A):	An aqueous solution of ammonium carbonate is basic.
Reason (R):	The acidic or basic nature of a salt solution of a salt of a weak acid and a weak base depends on the Ka and Kb values of the acid and the base forming it.

1.	Both (A) and (R) are true and (R) is the correct explanation of (A).
2.	Both (A) and (R) are true but (R) is not the correct explanation of (A).
3.	(A) is true but (R) is false.
4.	(A) is false but (R) is true.

Hint: K_b of

{NH}_{4} OH >

K_a of

H_{2} {CO}_{3}

The reaction is as follows:

If K_b of

{NH}_{4} OH >

K_a of

H_{2} {CO}_{3}

The solution is basic.

or, If K_a of

H_{2} {CO}_{3}

>K_b of

{NH}_{4} OH

; the solution is acidic. Hence, both assertion and reason are true and the reason is the

correct explanation of assertion.