Which one of the following compounds has the smallest molar mass?

• A. H2O
• B. CH4
• C. CO2
• D. NH3

Answer: (D)

Verified step by step guidance

1. Identify the molecular formula of each compound: H\_2O (water), CH\_4 (methane), CO\_2 (carbon dioxide), and NH\_3 (ammonia).
2. Determine the atomic masses of each element involved using the periodic table: Hydrogen (H) ≈ 1 g/mol, Carbon (C) ≈ 12 g/mol, Oxygen (O) ≈ 16 g/mol, Nitrogen (N) ≈ 14 g/mol.
3. Calculate the molar mass of each compound by summing the atomic masses of all atoms in its formula. For example, for H\_2O, molar mass = 2 × atomic mass of H + 1 × atomic mass of O.
4. Repeat the calculation for CH\_4, CO\_2, and NH\_3, carefully multiplying the atomic masses by the number of atoms in each molecule.
5. Compare the calculated molar masses of all four compounds to determine which one has the smallest molar mass.