What is the molar mass of hydrogen gas (H_2)?

• A. 1.01 g/mol
• B. 2.02 g/mol
• C. 28.02 g/mol
• D. 18.02 g/mol

Answer: (B)

Verified step by step guidance

1. Identify the chemical formula of hydrogen gas, which is \(\mathrm{H_2}\), meaning it consists of two hydrogen atoms bonded together.
2. Recall the atomic mass of a single hydrogen atom, which is approximately 1.01 g/mol.
3. Calculate the molar mass of hydrogen gas by multiplying the atomic mass of hydrogen by the number of atoms in the molecule: \$2 \times 1.01\ \mathrm{g/mol}$.
4. Express the molar mass as the sum of the masses of the two hydrogen atoms, which gives the total molar mass of \(\mathrm{H_2}\).
5. Conclude that the molar mass of hydrogen gas is approximately 2.02 g/mol based on the calculation.