Match List-I with List-II. List-I Mass of substance List-II Number...

For A: Molar mass of $H_2O = 18$ g/mol. Moles of $H_2O = \dfrac{1.8 \times 10^{-3}}{18} = 10^{-4}$. Since each $H_2O$ molecule has $3$ atoms, the number of atoms = $3 \times 10^{-4} \times N_A$.

For B: Molar mass of $H_2SO_4 = 98$ g/mol. Moles of $H_2SO_4 = \dfrac{9.8 \times 10^{-3}}{98} = 10^{-4}$. Since each $H_2SO_4$ molecule has $7$ atoms, the number of atoms = $7 \times 10^{-4} \times N_A$.

For C: Molar mass of $C = 12$ g/mol. Moles of $C = \dfrac{1.8 \times 10^{-3}}{12} = 1.5 \times 10^{-4}$. The number of atoms = $1.5 \times 10^{-4} \times N_A$.

For D: Molar mass of $NaCl = 58.5$ g/mol. Moles of $NaCl = \dfrac{5.85 \times 10^{-3}}{58.5} = 10^{-4}$. Since each $NaCl$ formula unit has $2$ atoms, the number of atoms = $2 \times 10^{-4} \times N_A$.

Thus, the correct matching is A-III, B-IV, C-II, D-I.

Answer: A-III, B-IV, C-II, D-I