Chemistry - Mole Concept Question with Solution | TestHub

Number of atoms $=\frac{\text{ mass }}{\text{ molar mass }}\times N_A$ x Number of atoms in 1 mole $\therefore$ Number of atoms in $4.25\mathrm{g}{\mathrm{NH}}_3$ $$\begin{array}{l}=\frac{4.25}{17}\times N_A\times 4\\ =N_A\end{array}$$ Number of atoms in $8\mathrm{g}$ $${\mathrm{O}}_2=\frac{8}{32}\times {\mathrm{N}}_A\times 2=\frac{N_{\mathrm{A}}}{2}$$ Number of atoms in $2\mathrm{g}$ $${\mathrm{H}}_2=\frac{2}{2}\times {\mathrm{N}}_A\times 2=2{\mathrm{N}}_{\mathrm{A}}$$ Number of atoms in $4\mathrm{g}$ $$\mathrm{He}=\frac{4}{4}\times N_A\times 1=N_A$$ Thus, $2\mathrm{g}{\mathrm{H}}_2$ contains the maximum number of atoms among the given.