What is the number of moles of water molecules required to prepare $n$ moles of methane from $n$ moles of methyl magnesium iodide?

Combustion of $50 \ mL$ methane is carried out with $150 \ mL$ of air containing $21 \%$ oxygen by volume. What will be the total volume of the gaseous mixture after the reaction? (Assume water is in the gaseous state and air contains $79 \%$ nitrogen by volume).
$CH_{4(g)} + 2O_{2(g)} \to CO_{2(g)} + 2H_2O_{(g)}$

What will be the volume of the mixture after the reaction? $litre$
$NH_3(4 \ litre) + HCl(1.5 \ litre) \to NH_4Cl(s)$

The mass of $N_2F_4$ produced by the reaction of $2.0 \ mol$ of $NH_3$ and $8.0 \ mol$ of $F_2$ is $0.5 \ mol.$ What is the per cent yield?
$2NH_3 + 5F_2 \to N_2F_4 + 6HF$

When $10 \ g$ of copper and $10 \ g$ of iodine are mixed,calculate the theoretical yield of $CuI$ according to the equation,$2Cu + I_2 \longrightarrow 2CuI$. (in $g$)

The combustion of $1 \, \text{mol}$ of methanol in the presence of $O_2$ releases $723 \, \text{kJ mol}^{-1}$ of heat. If $1 \, \text{mol}$ of $O_2$ is used during this process,how much heat in $\text{kJ}$ will be produced?