Question

In the following observation.

Acid	$K_{a_1}$	$K_{a_2}$	$(X)$
Oxalic acid	$5.9\times 10^{-2}$	$6.4\times 10^{-5}$
Ascorbic acid	$7.4\times 10^{-4}$	$1.6\times 10^{-12}$
Sulphurous acid	$1.7\times 10^{-2}$	$6.4\times 10^{-8}$
$(Y)$	Very large	$1.2\times 10^{-2}$
Carbonic acid	$4.3\times 10^{-7}$	$(Z)$
Citric acid	$7.4\times 10^{-4}$	$1.7\times 10^{-5}$	$4.0\times 10^{-7}$
Phosphoric acid	$7.5\times 10^{-3}$	$6.2\times 10^{-8}$	$4.2\times 10^{-13}$

$X,Y$ and $Z$ respectively are

• A. $K=K_{a_1}\times K_{a_2}$, phosphorous acid, $6.5\times 10^{-11}$
• B. $K_{a_3}$, phosphorous acid, $6.5\times 10^{-11}$
• C. $K=K_{a_1}\times K_{a_2}$, sulphuric acid, $5.6\times 10^{-11}$
• D. $K_{a_3}$, sulphuric acid, $5.6\times 10^{-11}$

Answer 1

Answer: (D)

Correct answer is (d) $K_{a_3}$, sulphuric acid, $5.6\times 10^{-11}$