What is the percentage composition of $C$ in methanoic anhydride?

The empirical formula of a compound is $C_2H_5O$ and its molecular weight is $90$. The molecular formula of the compound is:

$A$ transition metal $M$ forms a volatile chloride which has a vapour density of $94.8$. If it contains $74.75\%$ of chlorine,the formula of the metal chloride will be:

On analysis,a saturated hydrocarbon is found to contain $83.70\%$ carbon and $16.30\%$ hydrogen. The empirical formula will be (at. wt. of $C=12$, at. wt. of $H=1$).

An organic compound with a molecular weight of $60$ contains $C = 20\%$,$H = 6.67\%$,and $N = 46.67\%$,with the remainder being oxygen. Upon heating,the solid residue gives a violet color with alkaline copper sulfate solution. Identify the compound.

$0.833 \, \text{mol}$ of a hydrocarbon contains $10 \, \text{g}$ of hydrogen. If the empirical formula of the compound is $CH_2O$,determine its molecular formula.