Avogadro's law: equal moles mean equal molecules

Steps:

• Molar mass of Cl₂ is 71 g/mol, so moles in 71 g = 71 / 71 = 1 mol.
• Molar mass of H₂ is 2 g/mol, so moles in 2 g = 2 / 2 = 1 mol.
• Number of molecules = moles × Avogadro's constant (6.022 × 10²³).
• Ratio of molecules (Cl₂ : H₂) = 1 : 1.

Why A is correct:

• Avogadro's law states equal volumes (or moles at same T/P) of gases contain equal molecules; here, 1 mol each yields identical molecule counts.

Why the others are wrong:

• B and D: Ignore equal moles, falsely suggest fewer Cl₂ molecules.
• C: Reverses ratio, assuming more Cl₂ molecules despite equal moles.

Final answer: A