Consider the following reaction:
$3 PbCl_2 + 2 (NH_4)_3 PO_4 \rightarrow Pb_3(PO_4)_2 + 6 NH_4 Cl$
If $72 \ mmol$ of $PbCl_2$ is mixed with $50 \ mmol$ of $(NH_4)_3 PO_4$,then the amount of $Pb_3(PO_4)_2$ formed is $......... \ mmol$. (nearest integer)

At $100\,^oC$,a $1.5\,L$ vessel contains $0.4\,g$ of $O_2$ and $0.06\,g$ of $H_2$. $(a)$ What is the total pressure in the vessel? $(b)$ If the mixture reacts to form water at $100\,^oC$,which gas will remain in the vessel? What will be their partial pressures (in $,atm$)? $(R = 0.0821\, L\,atm\,mol^{-1}\,K^{-1})$.

Moles of conc. $HNO_3$ required to oxidise one mole of sulphur is :
$S + 6HNO_3 \rightarrow H_2SO_4 + 6NO_2 + 2H_2O$

When $30 \ mL$ of $H_2$ reacts with $20 \ mL$ of $O_2$ to form water,what is leftover when the reaction ends?

How much amount of $Al_2O_3$ will be formed when $5.4 \ g$ of $Al$ reacts with $10 \ g$ of $O_2$? .......... $g$

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?