Which of the following is likely to undergo racemization during alkaline hydrolysis?

What is enthalpy of formation of $$\mathrm{NH}_3$$ if bond enthalpies are as $$(\mathrm{N} \equiv \mathrm{N})=941 \mathrm{~kJ},(\mathrm{H}-\mathrm{H})=436 \mathrm{~kJ},(\mathrm{N}-\mathrm{H})=389 \mathrm{~kJ}$$ ?

Which of the following alkyl halide is treated with sodium metal to obtain $$2,2,3,3$$ - tetramethyl butane?

Electrical conductance due to all the ions in $$1 \mathrm{~cm}^3$$ of given solution is called as