When $500 \ mL$ of a gaseous hydrocarbon is burned in excess of $O_2$,it produces $2.5 \ L$ of $CO_2$ and $3.0 \ L$ of water vapor. What is the molecular formula of the hydrocarbon?

The number of molecules in $100 \, mL$ of $0.02 \, N$ $H_2SO_4$ is .....

$A$ 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).

Consider the reaction shown below. The percentage yield of the amide product is $......$ . (Round off to the Nearest Integer). (Given: Atomic mass: $C = 12.0 \, u, H = 1.0 \, u, N = 14.0 \, u, O = 16.0 \, u, Cl = 35.5 \, u$)
$C_6H_5COCl + (C_6H_5)_2NH \rightarrow C_6H_5CON(C_6H_5)_2 + HCl$
Given: $0.140 \, g$ of $C_6H_5COCl$ reacts with $0.388 \, g$ of $(C_6H_5)_2NH$ to produce $0.210 \, g$ of $C_6H_5CON(C_6H_5)_2$.

In the balanced combustion reaction of $1 \, mol$ of $C_xH_{2n-2}$ hydrocarbon,the coefficients of $O_2$,$CO_2$,and $H_2O$ will be respectively ...

$8 \ g$ of $CH_4$ is completely burnt in air. The number of moles of water produced are $.....$