What is the volume occupied by $2.5 \ mol$ of ammonia gas at $\text{STP}$ (in $dm^3$)?

$A$ sample of a metal oxide has the formula $M_{0.83}O_{1.00}$. The metal $M$ can exist in two oxidation states,$+2$ and $+3$. In the sample of $M_{0.83}O_{1.00}$,the percentage of metal ions existing in the $+2$ oxidation state is $.........\%$ (nearest integer).

$A$ bottle of cold drink contains $200 \, mL$ of liquid with $0.1 \, M$ $CO_2$. If $CO_2$ behaves ideally,what will be the volume of $CO_2$ gas at $STP$ in the cold drink solution (in $, L$)?

The solution of sulphuric acid contains $80\%$ by weight $H_2SO_4$. The specific gravity of this solution is $1.71$. Its normality is about:

$5 \ mL$ of $N \ HCl$,$20 \ mL$ of $N/2 \ H_2SO_4$,and $30 \ mL$ of $N/3 \ HNO_3$ are mixed together and the volume is made up to $1 \ L$. The normality of the resulting solution is:

What does the equation $2Al(s) + \frac{3}{2}O_2(g) \to Al_2O_3(s)$ represent?