Chemistry item bank part 2

The empirical formula for perchloric acid is HClO₄. Which compound could represent the molecular formula for perchloric acid?

• H₄Cl₄O₁₂

• H₂Cl₂O₆

• H₃Cl₃O₁₂

• HClO₈

Students perform several experiments recording the reactions in lab journals. The students write and balance the chemical equations for each reaction and include the state of matter notations for each compound. The equations are below. Which chemical involved in the student experiments is dissolved in water?

• Fe₂O₃

• Fe

• Mg(OH)₂

• MgO

The reaction between solid aluminum and liquid bromine is exothermic. This reaction creates the product aluminum bromide. What equation includes the correct formulas and demonstrates conservation of mass?

• Al(s) + Br₂(l) → AlBr₃(s)

• Al(s) + Br(l) → AlBr(s)

• Al(s) + 3Br(l) → AlBr₃(s)

• 2Al(s) + 3Br₂(l) → 2AlBr₃(s)

What are the correct coefficients if the law of conservation of mass is applied to the decomposition of solid ammonium nitrite to nitrogen gas and liquid water?

• 2, 2, 2

• 1, 1, 2

• 2, 1, 2

• 1, 2, 2

Students perform an experiment that instantaneously forms a precipitate. They mix aqueous iron (III) nitrate and sodium hydroxide to produce iron (III) hydroxide and aqueous sodium nitrate. What is the correct balanced equation for this reaction to show conservation of mass?

• 3FeNO₃ + 2NaOH → FeOH₃ + 3NaNO₃

• FeN + 3NaOH → FeOH₃ + 3NaN

• Fe(NO₃)₃ + 3NaOH → Fe(OH)₃ + 3NaNO₃

• Fe³⁺NO₃⁻ + Na⁺OH⁻ → Fe³⁺OH⁻ + Na⁺NO₃⁻

In a lab report, students must write out the word equation for Zn + Pb(NO₃)₂ → Zn(NO₃)₂ + Pb. What is the correct word equation?

• Zinc and lead nitrate react to form zinc nitrate and lead.

• Zinc and lead (II) nitrate react to form zinc nitrate and lead.

• Zinc and lead nitrogen oxide react to form zinc nitrogen oxide and lead.

• Zinc and lead (II) nitrate react to form zinc nitrite and lead (II).

What are the coefficients that would correctly balance this reaction?

• 1, 2, 1

• 2, 2, 1

• 2, 1, 1

• 2, 2, 2

What are the coefficients that would correctly balance this reaction?

• 2, 1, 2, 1

• 1, 2, 3, 1

• 1, 2, 1, 2

• 1, 1, 2, 1

What is the balanced equation for the combustion of magnesium?

• Mg (s) + O2 (g) → MgO (g)

• Mg (s) + O2 (g) → MgO2 (g)

• 2 Mg (s) + O2 (g) → 2 MgO (s)

• Mg (s) + 2 O2 (g) → MgO4^2- (aq)

Which coefficients are required to correctly balance the equation, C2H2 + O2 → CO2 + H2O?

• 1, 2, 3, 2

• 2, 5, 4, 2

• 2, 4, 5, 2

• 2, 3, 5, 2