Which one of the following has the maximum number of atoms?

Solution & Explanation

\textbf{Answer:} (B) 1 g of $\mathrm{Li}$ \textbf{Solution:} Number of atoms $=\frac{\text{mass}}{\text{molar mass}}\times N_A\times (\text{atoms per formula unit})$. For a fixed 1 g, the species with the smallest molar mass per atom gives the most atoms. $\mathrm{Li}$ (7 g mol${}^{-1}$, monatomic) has the lowest atomic mass, so 1 g of $\mathrm{Li}$ gives the maximum number of atoms.