Consider the following data

Heat of combustion of $$\mathrm{H}_{2}(\mathrm{g})\quad\quad=-241.8 \mathrm{~kJ} \mathrm{~mol}^{-1}$$

Heat of combustion of $$\mathrm{C}(\mathrm{s})\quad\quad=-393.5 \mathrm{~kJ} \mathrm{~mol}^{-1}$$

Heat of combustion of $$\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(\mathrm{l})\quad=-1234.7 \mathrm{~kJ}~{\mathrm{mol}}^{-1}$$

The heat of formation of $$\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OH}(\mathrm{l})$$ is $$(-)$$ ___________ $$\mathrm{kJ} ~\mathrm{mol}^{-1}$$ (Nearest integer).

Number of isomeric aromatic amines with molecular formula $$\mathrm{C}_{8} \mathrm{H}_{11} \mathrm{~N}$$, which can be synthesized by Gabriel Phthalimide synthesis is ____________.

The equilibrium composition for the reaction $$\mathrm{PCl}_{3}+\mathrm{Cl}_{2} \rightleftharpoons \mathrm{PCl}_{5}$$ at $$298 \mathrm{~K}$$ is given below:

$$\left[\mathrm{PCl}_{3}\right]_{\mathrm{eq}}=0.2 \mathrm{~mol} \mathrm{~L}^{-1},\left[\mathrm{Cl}_{2}\right]_{\mathrm{eq}}=0.1 \mathrm{~mol} \mathrm{~L}^{-1},\left[\mathrm{PCl}_{5}\right]_{\mathrm{eq}}=0.40 \mathrm{~mol} \mathrm{~L}^{-1}$$

If $$0.2 \mathrm{~mol}$$ of $$\mathrm{Cl}_{2}$$ is added at the same temperature, the equilibrium concentrations of $$\mathrm{PCl}_{5}$$ is __________ $$\times 10^{-2} \mathrm{~mol} \mathrm{~L}^{-1}$$

Given : $$\mathrm{K}_{\mathrm{c}}$$ for the reaction at $$298 \mathrm{~K}$$ is 20

In an ice crystal, each water molecule is hydrogen bonded to ____________ neighbouring molecules.