Question

In each of the following questions, two statements are given: statement -1 and statement -2. Examine the statements carefully and answer the questions according to the instructions given below:

Statement 1: $H_{3}P{O}_4$ is the most acidic among $H_{3}P{O}_4,H_{3}P{O}_3\text{and}{H}_{3}P{O}_2$.

Statement 2: In general, the acidity of oxyacids increases with the increase in percentage of oxygen.

• A. Statement -1 is true, statement -2 is true; statement -2 is the correct explanation for statement -1.
• B. Statement -1 is true, statement -2 is true; statement -2 is NOT the correct explanation for statement -1.
• C. Statement -1 is true, statement -2 is false.
• D. Statement -1 is false, Statement -2 is true.

Answer 1

The correct option is D Statement -1 is false, Statement -2 is true.

The correct order of acidity is $H_{3}P{O}_2>H_{3}P{O}_3>H_{3}P{O}_4$

More the number of double bonded oxygens to phosphorous and lesser the number of $-OH$ groups, more resonance stablised congugate base is formed and hence the acidity of given oxoacid will be higher.

The acidity of oxyacids increases with the increase in percentage of oxygen. This is because, oxygen is highly electronegative and therefore pulls the electron cloud towards itself and thus releases protons easily.