Match List-I with List-II. List-I Mass of substance List-II Number of atoms A. 1.8 mg water I. 2 10^ -4 N_A B. 9.8 mg sulphuric acid II. 1.5 10^ -4 N_A C. 1.8 mg carbon III. 3 10^ -4 N_A D. 5.85 mg salt (NaCl) IV. 7 10^ -4 N_A Choose the correct answer from the options given below:
C. A-III, B-IV, C-II, D-I
For A: Molar mass of H_2O = 18 g/mol. Moles of H_2O = 1.8 10^ -3 18 = 10^ -4 . Since each H_2O molecule has 3 atoms, the number of atoms = 3 10^ -4 N_A. For B: Molar mass of H_2SO_4 = 98 g/mol. Moles of H_2SO_4 = 9.8 10^ -3 98 = 10^ -4 . Since each H_2SO_4 molecule has 7 atoms, the number of atoms = 7 10^ -4 N_A. For C: Molar mass of C = 12 g/mol. Moles of C = 1.8 10^ -3 12 = 1.5 10^ -4 . The number of atoms = 1.5 10^ -4 N_A. For D: Molar mass of NaCl = 58.5 g/mol. Moles of NaCl = 5.85 10^ -3 58.5 = 10^ -4 . Since each NaCl formula unit has 2 atoms, the number of atoms = 2 10^ -4 N_A. Thus, the correct matching is A-III, B-IV, C-II, D-I. Answer: A-III, B-IV, C-II, D-I
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