The molecular formula of the chloride of a metal $M$ is $MCl_3$. The formula of its carbonate would be:

$A$ hydrocarbon contains $80\%$ carbon and its vapor density is $15$. What is the hydrocarbon?

$A$ compound possesses $8\%$ sulphur by mass. The least molecular mass is

The ratio of the mass percentages of $C$ and $H$ and $C$ and $O$ of a saturated acyclic organic compound $X$ are $4 : 1$ and $3 : 4$ respectively. Then,the moles of oxygen gas required for complete combustion of two moles of organic compound $X$ is

An oxide of iron,which contains $69.9 \%$ iron and $30.1 \%$ dioxygen by mass,has the empirical formula:

$0.44 \ g$ of a colourless oxide of nitrogen occupies $224 \ mL$ at $\text{STP}.$ The compound is $-$