$A$ compound contains $C = 90\%$ and $H = 10\%$. The empirical formula of the compound is:

An organic compound contains $69 \%$ carbon and $4.8 \%$ hydrogen,the remainder being oxygen. Calculate the masses of carbon dioxide and water produced when $0.20 \ g$ of this substance is subjected to complete combustion.

Determine the empirical formula of Kevlar,used in making bulletproof vests,which contains $70.6 \% \, C, \, 4.2 \% \, H, \, 11.8 \% \, N$ and $13.4 \% \, O$.

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 $C: 12, H: 1, O: 16, Cl: 35.5$)

If the fertilizers listed below are priced according to their nitrogen content,which will be the least expensive per $50 \ kg$ bag?

Urea is a better fertilizer than ammonium sulphate because