MCQEasyJEE 2023Group 15 Elements

JEE Chemistry 2023 Question with Solution

The number of P–O–P bonds in H4P2O7\mathrm{H_4P_2O_7}, (HPO3)3(\mathrm{HPO_3})_3 and P4O10\mathrm{P_4O_{10}} are respectively

  • A

    0,3,40, 3, 4

  • B

    0,3,60, 3, 6

  • C

    1,2,41, 2, 4

  • D

    1,3,61, 3, 6

Answer

Correct answer:D

Step-by-step solution

Standard Method

Given: The compounds are H4P2O7\mathrm{H_4P_2O_7}, (HPO3)3(\mathrm{HPO_3})_3 and P4O10\mathrm{P_4O_{10}}.

Find: The number of P–O–P bonds in each compound.

A P–O–P bond is counted only when an oxygen atom bridges two phosphorus atoms.

For H4P2O7\mathrm{H_4P_2O_7}, two PO4\mathrm{PO_4} tetrahedra are joined by one bridging oxygen atom. Therefore, it contains one P–O–P linkage.

Number of P–O–P bonds in H4P2O7=1\text{Number of P–O–P bonds in } \mathrm{H_4P_2O_7} = 1

For (HPO3)3(\mathrm{HPO_3})_3, the structure is a cyclic ring of three PO3\mathrm{PO_3} units linked through oxygen atoms. Each linkage between two phosphorus atoms is one P–O–P bond, so the three-membered ring contains three such bonds.

Number of P–O–P bonds in (HPO3)3=3\text{Number of P–O–P bonds in } (\mathrm{HPO_3})_3 = 3

For P4O10\mathrm{P_4O_{10}}, the cage structure contains bridging oxygen atoms connecting phosphorus atoms. The total number of such P–O–P linkages is six.

Number of P–O–P bonds in P4O10=6\text{Number of P–O–P bonds in } \mathrm{P_4O_{10}} = 6

Thus, the required numbers are 1,3,61, 3, 6. Therefore, the correct option is D.

Common mistakes

  • Counting terminal P=O\mathrm{P=O} bonds as P–O–P bonds is incorrect because P–O–P requires one oxygen to bridge two phosphorus atoms. Count only bridging oxygens.

  • In (HPO3)3(\mathrm{HPO_3})_3, treating the compound as a linear structure gives the wrong count. It is a cyclic trimer, so the ring contains three P–O–P linkages.

  • For P4O10\mathrm{P_4O_{10}}, ignoring the cage framework leads to undercounting. Separate terminal oxygens from bridging oxygens, then count only the bridging P–O–P connections.

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