In P4O10 all P-O bonds are counted as sigma bonds (6 bridging O atoms with two bonds each and 4 terminal O atoms with one sigma bond each); in P4O6 the structure has only the 6 bridging O atoms. The total number of P-O sigma bonds in P4O10 minus that in P4O6 is

JEE Advanced levelSingle correct optionDifficulty 3 of 3pn103

In $P X_{4} O X_{10}$ all P-O bonds are counted as sigma bonds (6 bridging O atoms with two bonds each and 4 terminal O atoms with one sigma bond each); in $P X_{4} O X_{6}$ the structure has only the 6 bridging O atoms. The total number of P-O sigma bonds in $P X_{4} O X_{10}$ minus that in $P X_{4} O X_{6}$ is

P X_{4} O X_{10}

6 \times 2 + 4 \times 1 = 16

sigma bonds.

P X_{4} O X_{6}

6 \times 2 = 12

sigma bonds. Difference = 4 (one per terminal P=O).