Molecular Mass and Mole Concepts and Problems

1. How many atoms are in 16.3 g of S?

2.00 × 10²³ S atoms 6.02 × 10²³ S atoms 3.06 × 10²³ S atoms 1.00 × 10²³ S atoms

2. What is molecular mass (or molecular weight)?

The mass of one atom The number of atoms in a molecule The number of molecules in a mole The total mass of a molecule expressed in atomic mass units (amu)

3. What is the molar mass of an atom?

Number of atoms in a molecule Mass of 1 mole of atoms (g) Mass of 1 molecule (g) Mass of 1 atom (amu)

4. What is a mole (n)?

Quantity of substance containing as many elementary entities as atoms in exactly 12 grams of carbon-12 Mass of one molecule Mass of one atom Number of atoms in one molecule

5. What is the formula for calculating molecular mass?

Sum of electrons in the molecule Sum of atomic numbers of all atoms Sum of (atomic mass of each element × number of atoms of that element) Sum of protons and neutrons

6. How many grams of Fe are in 2.5 moles of Fe?

139.6 g Fe 100 g Fe 55.8 g Fe 250 g Fe

7. How many moles of CO₂ are present in 22.4 g of CO₂?

0.224 mol CO₂ 1.00 mol CO₂ 2.24 mol CO₂ 0.507 mol CO₂

8. How many oxygen atoms are present in 18.0 g of H₂O?

3.01 × 10²³ oxygen atoms 1.00 × 10²³ oxygen atoms 12.04 × 10²³ oxygen atoms 6.02 × 10²³ oxygen atoms

9. What is Avogadro’s number (Nₐ)?

1.602 × 10⁻¹⁹ 9.81 3.14 × 10²³ 6.022 × 10²³

10. How many moles of Ne are in 10.2 g of Ne?

0.507 mol Ne 5.07 mol Ne 0.102 mol Ne 1.02 mol Ne