The acid salt obtained by neutralising two of the four acidic hydrogens of diphosphoric acid, H4P2O7, with NaOH has the formula Na2H2P2O7. Which option gives its IUPAC name and the oxidation number of P?

disodium dihydrogendiphosphate, +5

disodium dihydrogendiphosphate, +4

disodium dihydrogendiphosphate, +5

JEE Advanced levelSingle correct optionDifficulty 3 of 3bn150

The acid salt obtained by neutralising two of the four acidic hydrogens of diphosphoric acid, $H X_{4} P X_{2} O X_{7}$ , with NaOH has the formula $Na X_{2} H X_{2} P X_{2} O X_{7}$ . Which option gives its IUPAC name and the oxidation number of P?

The anion is

H X_{2} P X_{2} O X_{7} X^{2 -}

: two H and two P, so dihydrogendiphosphate, with two Na as disodium. Oxidation number:

2 + 2 + 2 x - 14 = 0

gives

x = + 5