Assertion (A): There is very little difference in acid strength of `H_(3)PO_(4), H_(3)PO_(3)`,and `H_(3)PO_(2)`.
Reason (R) : The hydrogens in these acids are not all bonded to oxygens. The electrone-grativities of `P` and `H` are almost the same.

Options

A. If both (A) and (R) are correc, and (R) is the correct explanation of (A).
B. If both (A) and (R) are correct but (R) is not the correct explanation of (A).
C. If (A) is correct, but (R) is incorrect.
D. If (A) is incorrect, but (R) is correct.

Answer

A

Explanation

Both `(A)` and `(R)` are correct and `(R)` is the correct explanation of `(A)`. Structures are:
`underset((H_(3)PO_(4))("Tribasic acid"))(HO-overset(O)overset(||)underset(OH)underset(|)(P)-OH), underset((H_(3)PO_(4))("Dibasic acid"))(H-overset(O)overset(||)underset(OH)underset(|)(P)-OH)underset((H_(3)PO_(4))("Monobasic acid"))(H-overset( :O: )overset(||)underset(H)underset(|)(P)-OH)`
(In all the three acids, number of terminal oxygen atoms is one).