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

$92 \ g$ of $NO_{2(g)}$ and $32 \ g$ of $O_{2(g)}$ are taken in a rigid container. At a constant temperature,they react to produce $N_2O_{5(g)}$. The pressure in the container after the reaction is observed to be $\frac{7}{8} P$,where $P$ is the initial pressure of the gaseous mixture. The percentage yield of the reaction is ....$\%$

One mole of calcium phosphide on reaction with excess water gives

$5 \, \text{moles}$ of $A$,$6 \, \text{moles}$ of $B$,and an excess amount of $C$ are mixed to produce a final product $D$,according to the reactions:
$A + 2B \to I$
$I + C \to B + D$
What is the maximum number of moles of $D$ that can be produced,assuming that the products formed can be reused in the reactions?

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?

$A$ $10.0 \, L$ vessel contains $O_2$ at a partial pressure of $600 \, torr$ and $H_2$ at a partial pressure of $400 \, torr$. The gases react according to the following equation upon electric sparking: $H_{2(g)} + \frac{1}{2}O_{2(g)} \to H_2O_{(g)}$. If the reaction goes to completion,which of the following is correct?