When $81.0 \ g$ of aluminium is allowed to react with $128.0 \ g$ of oxygen gas,the mass of aluminium oxide produced in grams is $..........$ $(Nearest \ integer)$. Given: Molar mass of $Al$ is $27.0 \ g \ mol^{-1}$,Molar mass of $O$ is $16.0 \ g \ mol^{-1}$.

How many moles of $P_4$ can be produced by reaction of $0.10 \ mol$ $Ca_5(PO_4)_3F$,$0.36 \ mol$ $SiO_2$,and $0.90 \ mol$ $C$ according to the following reaction?
$4Ca_5(PO_4)_3F + 18SiO_2 + 30C \to 3P_4 + 2CaF_2 + 18CaSiO_3 + 30CO$

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

$A$ $10.0 \, L$ 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?

When $35 \ mL$ of $0.15 \ M$ lead nitrate solution is mixed with $20 \ mL$ of $0.12 \ M$ chromic sulphate solution,$....... \times 10^{-5}$ moles of lead sulphate precipitate out. (Round off to the Nearest Integer).

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 $g$)