Pick out the incorrect statement.

Options

A. Orthophosphorus acid can be obtained by reacting `P_O_6" wIth "H_O`
B. Orthophosphoric acid can be obtained by reacting `P_4O_10" with "H_O`
C. Pyrophosphoric can be obtained by heating orthophosphorus acid
D. Metaphosphoric acid is obtained by the dehydration of orthophosphoric acid at `316^@C.`

Answer

C

Explanation

Pyrophosphoric acid can be obtained by heating orthophosphoric acid.
`O-underset(OH)underset(|)overset(OH)overset(|)(P)-OH+H" "O+underset(OH)underset(|)overset(OH)overset(|)(P)=O to O-underset(OH)underset(|)overset(OH)overset(|)(P)-O-underset(OH)underset(|)overset(OH)overset(|)(P)=O+H_(2)O`
Although pyrophosphoric is tetrabais acid, yet only two sodium salts are known `Na_(2)P_(2)O_(7) and Na_2H_(2)P_(2)O_(7)`.
`P_(4)O_(6)+6H_(2)O to 4H_(3)PO_(3) `
It structure is `O=underset(OH)underset(|)overset(H)overset(|)P-OH`
Therefore, it is diabastic
(b) `P_(4)O_(10)+6H_(2)O to 4 [O=underset(OH)underset(|)overset(OH)overset(|)P-OH]`
This acid is tribasic.
(d) `H_(3)PO_(4) overset(316^(@)C)to HPO_(3)+H_(2)O`
The metaphosphate ions up form `PO_(4)` units and are cyclic. The trimetaphosphate ion `(P_(3)O_(9)^(3-))` is shown below: