Which of the following compound has square pyramidal structure?

Which of the following metal halides have more covalent character?

What ratio by mass of 'Ne' and $\text{CH}_4$ should be mixed so that partial pressure exerted by each gas is same?

Calculate $\Delta\text{H}$ for the following reaction at $300\ \text{K}$
$2\text{C}_{(s)} + 3\text{H}_{2(g)} \longrightarrow \text{C}_2\text{H}_{6(g)}$ if $\Delta\text{U}$ for the reaction is $-80\ \text{kJ}$ ($\text{R} = 8.314\ \text{JK}^{-1}\text{mol}^{-1}$)