$P_4O_{10}$ has short and long $P-O$ bonds. The number of short $(P=O)$ bonds in this compound is:

The number of different types of bonds present in $P_4O_{10}$ is:

The ionization enthalpy of $Na^{+}$ formation from $Na_{(g)}$ is $495.8 \ kJ \ mol^{-1},$ while the electron gain enthalpy of $Br_{(g)}$ is $-325.0 \ kJ \ mol^{-1}$. Given the lattice enthalpy of $NaBr_{(s)}$ is $-728.4 \ kJ \ mol^{-1}$. The energy for the reaction $Na_{(g)} + Br_{(g)} \rightarrow NaBr_{(s)}$ is $(-) \dots \dots \dots \dots \dots \times 10^{-1} \ kJ \ mol^{-1}$.

The Born-Haber cycle can be used to estimate:

Which of the following molecules is theoretically not possible?

The Lewis acid strength of $BF_3, BCl_3,$ and $BBr_3$ decreases in the following order: