Question

Which one of the following is true for any diprotic acid, $H_{2}X$ ?

• A. $K{a}_2=K{a}_1$
• B. $K{a}_2>K{a}_1$
• C. $K{a}_1>K{a}_2$
• D. $K{a}_2=1/K{a}_1$

Answer 1

Answer: (C)

$H_{2}X\rightleftharpoons H^{+}+H{X}^{-}\left(K{a}_1\right)$
$H{X}^{-}\rightleftharpoons H^{+}+X^{2-}\left(K{a}_2\right)$
So $K{a}_1>K{a}_2$