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?

An organic compound contains carbon,hydrogen,and oxygen. Its elemental analysis gave $C = 38.71 \%$ and $H = 9.67 \%$. The empirical formula of the compound would be:

$A$ compound contains $2.34 \ g$ of nitrogen and $5.34 \ g$ of oxygen. What is the empirical formula of the compound?

If the percentage of $Se$ (atomic weight $78.4$) in a peroxidase anhydrous enzyme is $0.5\%$,what is the minimum molecular weight of the peroxidase anhydrous enzyme?

Arrange the following compounds in the increasing order of percentage of chlorine by weight:
$I.$ $DDT$ $(C_{14}H_9Cl_5)$
$II.$ Gammaxene $(C_6H_6Cl_6)$
$III.$ Carbon tetrachloride $(CCl_4)$
$IV.$ Chlorobenzene $(C_6H_5Cl)$

$25 \ g$ of an unknown hydrocarbon upon burning produces $88 \ g$ of $CO_2$ and $9 \ g$ of $H_2O$. This unknown hydrocarbon contains: