The mass of $112 \ cm^3$ of $NH_3$ gas at $STP$ is (in $g$)

Which one of the following statements is incorrect?

Which of the following substances consists of a total of $1 \ mol$ of atoms? (Molar mass of $NH_3 = 17 \ g/mol, H_2O = 18 \ g/mol, N_2 = 28 \ g/mol, CO_2 = 44 \ g/mol$)

If a gaseous mixture contains $20\%$ $H_2$ by weight,what is the number of moles of $H_2$ in $100 \ g$ of the mixture (in $mol$)?

Calculate the number of atoms in each of the following:
$(i)$ $52$ moles of $Ar$
$(ii)$ $52$ $u$ of $He$
$(iii)$ $52$ $g$ of $He$.

Mass of $0.1 \ mol$ of methane is (in $g$)