Which of the following relations gives the value of $n$ in the context of empirical and molecular formulas?

$116 \ g$ of a substance upon dissociation reaction,yields $7.5 \ g$ of hydrogen,$60 \ g$ of oxygen and $48.5 \ g$ of carbon. Given that the atomic masses of $H, O$ and $C$ are $1, 16$ and $12$ respectively. The data agrees with how many formulae of the following?
$(A)$ $CH_3COOH$
$(B)$ $HCHO$
$(C)$ $CH_3OOCH_3$
$(D)$ $CH_3CHO$

$A$ compound has $50\%$ carbon,$50\%$ oxygen and its approximate molecular weight is $290$. Its molecular formula is

Provide information on the percentage proportion of elements and mixtures present in Portland cement.

In a compound formed by element $X$ (atomic mass = $75$) and element $Y$ (atomic mass = $16$),if the percentage of $X$ is $75.8\%$,what will be its empirical formula?

The percentage of nitrogen in urea is about