An ornamental of gold having $75\%$ of gold,it is of .............. carat.

An oxide of iron contains $69.9\%$ iron. Its empirical formula is: (Given: Molar mass of $Fe$ and $O$ are $56$ and $16 \text{ g mol}^{-1}$ respectively.)

The formula of a substance is $(CO)_x$. If its vapor density is $70$,find the value of $x$.

Substances $X$ and $Y$ have the same mass. If their atomic weights are $30$ and $20$ respectively,and the molecular weight of the compound is $120$,what is the molecular formula of the compound?

$A$ carbohydrate with the empirical formula $CH_2O$ contains $1 \ g$ of hydrogen in $0.1 \ mol$ of the compound. Determine the molecular formula of the carbohydrate.

Quantitative analysis of an organic compound $(X)$ shows the following percentage composition: $C: 14.5\%$,$Cl: 64.46\%$,and $H: 1.8\%$. The empirical formula mass of the compound $(X)$ is $.......... \times 10^{-1}$. (Given molar mass in $g \ mol^{-1}$ of $C: 12, H: 1, O: 16, Cl: 35.5$)