Actual number of atoms of different elements present in a molecule of a compound is given by

An organic compound contains $C$,$H$ and $S$. The minimum molecular weight of the compound containing $8\%$ sulphur is........$g\,mol^{-1}$ (atomic weight of $S = 32\,amu$)

Which of the following pairs of species has the same percentage of carbon?

An organic compound has been found to possess the empirical formula $CH_2O$ and molecular weight $90$. The molecular formula of it is $(C = 12, H = 1, O = 16)$.

Urea is a better fertilizer than ammonium sulphate because

Chlorophyll, the green pigment in plants responsible for photosynthesis, contains $2.68\%$ of magnesium by mass. Calculate the number of magnesium atoms in $2.00 \ g$ of chlorophyll.