How many hydrogen atoms are surrounding each oxygen atom in structure of ice?

Which of the following is not an example of antiseptic drug?

Which of the following compounds is obtained, when phenol react with bromine water?

What is standard $N \equiv N$ bond enthalpy from following reaction,

$$\begin{aligned} & \mathrm{N}_2(g)+3 \mathrm{H}_2(g) \longrightarrow 2 \mathrm{NH}_3(g) ; \Delta H^{\circ}=-83 \mathrm{~kJ} \\ & \left(\Delta H^{\circ}(\mathrm{H}-\mathrm{H})=435 \mathrm{~kJ} ; \Delta H^{\circ}(\mathrm{N}-\mathrm{H})=389 \mathrm{~kJ}\right) \\ \end{aligned}$$