Calculations Quiz 1

Which of the following is the correct value for Avogadro’s number?

• 6.022 × 10²³

• 6.23 × 10²²

• 6.023 × 10²²

• 6.22 × 10²³

Avogadro’s number is based on the number of atoms in exactly 12 g of _______.

• Nitrogen-14

• Hydrogen-1

• Oxygen-16

• Carbon-12

How many atoms are in 3.00 kg of copper?

• 2.84 × 10²⁴ atoms Cu

• 2.84 × 10²⁵ atoms Cu

• 3.54 × 10²⁴ atoms Cu

• 3.54 × 10²⁵ atoms Cu

An element’s atomic mass, expressed in atomic mass units on the periodic table, is equal to its ______ mass.

• Actual

• Molar

• Theoretical

• Empirical

What is the molar mass of Pb(SO₄)₂?

• 504.7 g/mol

• 367.3 g/mol

• 399.3 g/mol

• 414.4 g/mol

Which formula gives the simplest whole-number ratio of the atoms in a compound?

• Structural

• Molecular

• Empirical

• Stoichiometric

What is the empirical formula of a compound containing 80.00% C and 20.00% H?

• C₂H₆

• CH₃

• C₇H₂₀

• C₈₀H₂₀

Which formula best represents the arrangement of bonds in a molecule?

• Molecular

• Structural

• Empirical

• Ionic

Which of the following factors is required to calculate the percent composition of a compound?

• The molar mass of the compound

• The density of the elements

• The temperature of the compound

• The oxidation numbers

The percent composition of benzoic acid is 68.85% C, 4.95% H, and 26.21% O. What is its empirical formula?

• C₃H₄O₃

• C₅H₇O₂

• C₆H₅O₂

• C₇H₆O₂