Insulin contains $3.4\%$ sulfur. What is the minimum molecular weight of insulin?

On complete combustion,$1.4 \, g$ of a hydrocarbon gave $1.8 \, g$ of water. The empirical formula of the hydrocarbon is:

In an $80 \, g$ compound,the masses of elements are $C = 24 \, g$,$H = 4 \, g$,and $O = 32 \, g$. Find its empirical formula.

Calculate the percentage composition of the following elements:
$(a)$ Sulphur in $CN_4H_4S$
$(b)$ Carbon in $C_2H_4O_2$
$(c)$ Nitrogen in $CN_2H_2O$
$(d)$ Hydrogen in $C_6H_6$
Given atomic masses: $C = 12, H = 1, O = 16, N = 14, S = 32$.

How much copper can be obtained from $100 \ g$ of copper sulfate $(CuSO_4)$ (in $g$)?

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