Question

P-P bond is present in:
(A) ${{P}_{4}}{{O}_{10}}$
(B) ${{P}_{4}}{{O}_{6}}$
(C) ${{H}_{4}}{{P}_{2}}{{O}_{6}}$
(D) ${{H}_{4}}{{P}_{2}}{{O}_{7}}$

Answer 1

Hint: P-P bond means that the two phosphorous atoms are joined with each other which leads to formation of a bridge between the molecules. P-P is a covalent bond which is formed by the sharing of electrons by different atoms which are present in the molecule.

Complete step by step solution:
Hypophosphoric acid i.e. ${{H}_{4}}{{P}_{2}}{{O}_{6}}$ , in this hypo means beneath or less than. The Hypophosphoric acid has an oxidation state of +4 between the phosphorus acid and the phosphoric acid.
The oxidation state of P in${{P}_{4}}{{O}_{10}}$, ${{P}_{4}}{{O}_{6}}$ and ${{H}_{4}}{{P}_{2}}{{O}_{7}}$ is +5. The calculated oxidation state is equal to the maximum oxidation state of phosphorus hence there is P-O-P bond present in all these compounds.
Among the given options Hypophosphoric acid i.e. ${{H}_{4}}{{P}_{2}}{{O}_{6}}$ forms a P-P double bond because the oxidation state if +4 which is less than the maximum oxidation state of P. and when the calculated oxidation state is less than the maximum oxidation state then there is a direct linkage between the elements here it is P-P linkage.
The structure of Hypophosphoric acid i.e. ${{H}_{4}}{{P}_{2}}{{O}_{6}}$ is shown below:

In this structure we can note that there are two P-O bonds having bond length of 151 pm and four P-OH bonds having bond length of 151 pm and one P-P single bond having bond length of 219 pm.

Hence the correct answer is option ©

Note: Hypophosphoric acid i.e. ${{H}_{4}}{{P}_{2}}{{O}_{6}}$ is used as a bleaching agent. It is also used as a reducing agent, as a stimulant and pharmaceutical agent and also as a wetting agent. Hypophosphoric acid is a mineral acid which is present as dehydrate in the solid state.