Question

Acidity of diprotic acids in aqueous solutions increases in the order:

• A. $H_{2}S<H_{2}Se<H_{2}Te$
• B. $H_{2}Se<H_{2}S<H_{2}Te$
• C. $H_{2}Te<H_{2}S<H_{2}Se$
• D. $H_{2}Se<H_{2}Te<H_{2}S$

Answer 1

The correct option is A $H_{2}S<H_{2}Se<H_{2}Te$

The strength of acid is directly proportional to stability of its conjugated bases.

With increase in the atomic size, the strength of the bond between hydrogen and the central atom decreases. This facilitates the release of proton.

Also the charge density decreases from $O^{2-}$ ion to $T{e}^{2-}$ ion.The oxide ion is the smallest, has maximum resistance to dissociation and has maximum affinity for proton and is strongest base. Hence, water is the weakest acid and hydrogen telluride is the strongest hydride.

Acidity of diprotic acids in aqueous solutions increases in the order $H_{2}O<H_{2}S<H_{2}Se<H_{2}Te$ .

Therefore, the correct option is $A$.