Unit 7 EXAM: Stoichiometry

What is the total number of atoms contained in a 1.00-mole sample of helium?

• 1.00 atom

• 2.00 atoms

• 1.20 × 10²⁴ atoms

• 6.02 × 10²³ atoms

A sample of a compound contains 65.4 grams of zinc, 12.0 grams of carbon, and 48.0 grams of oxygen. What is the mole ratio of zinc to carbon to oxygen in this compound?

• 1:4:6

• 5:1:4

• 1:1:2

• 1:1:3

What is the gram-formula mass of Fe(NO₃)₃?

• 146 g/mol

• 194 g/mol

• 214 g/mol

• 242 g/mol

The total number of moles represented by 20 grams of CaCO₃ is

• 1

• 2

• 0.1

• 0.2

Given the balanced equation: CaCO₃(s) + 2HCl(aq) → CaCl₂(aq) + H₂O(l) + CO₂(g), what is the total number of moles of CO₂ formed when 20. moles of HCl is completely consumed?

• 20. mol

• 40. mol

• 10. mol

• 5.0 mol

Given the formula representing a hydrocarbon: the molecular formula and the empirical formula for this hydrocarbon are

• C₄H₈ and CH₃

• C₅H₁₀ and CH₃

• C₄H₈ and CH₂

• C₅H₁₀ and CH₂

Which equation illustrates conservation of mass?

• H₂ + O₂ → 2 H₂O

• H₂ + Cl₂ → HCl

• H₂ + O₂ → H₂O

• H₂ + Cl₂ → 2 HCl

Given the balanced equation representing a reaction: 2NO + O₂ → 2NO₂ + energy, the mole ratio of NO to NO₂ is

• 5 to 2

• 2 to 1

• 3 to 2

• 1 to 1

What is the mass in grams of 2.0 moles of NO₂?

• 60.

• 46

• 30.

• 92

What is the total number of atoms of oxygen in the formula Al(ClO₃)₃ • 6H₂O?

• 15

• 9

• 10

• 6