Types of Reactions — Drills · Grade 11 Science

What these drills covers

By the end of Types of Reactions you should be able to:

I can classify a reaction as synthesis, decomposition, single replacement, double replacement, or combustion by looking at the pattern of its reactants and products.
I can predict the products of a simple reaction once I know its type and the way the atoms recombine.

6 questions, multiple choice and written answer, each with a worked explanation.

Vocabulary used: synthesis reaction, decomposition reaction, single-replacement reaction, double-replacement reaction, combustion reaction, activity series.

Problem 1

A single compound splits into two or more simpler substances, AB → A + B. What type of reaction is this?

single replacement
double replacement
synthesis
decomposition

Answer and explanation

decomposition

One substance breaking into simpler pieces is a decomposition reaction.

Problem 2

Which of these is a synthesis reaction?

2H₂ + O₂ → 2H₂O
CaCO₃ → CaO + CO₂
Zn + 2HCl → ZnCl₂ + H₂
CH₄ + 2O₂ → CO₂ + 2H₂O

Answer and explanation

2H₂ + O₂ → 2H₂O

Two elements combining into a single compound (A + B → AB) is synthesis.

Problem 3

Classify the neutralization reaction HCl + NaOH → NaCl + H₂O.

single replacement
double replacement
synthesis
decomposition

Answer and explanation

double replacement

Two compounds exchange partners (AB + CD → AD + CB), so it is double replacement.

Problem 4

The complete combustion of a hydrocarbon always produces which two products?

hydrogen and oxygen
carbon monoxide and hydrogen
carbon dioxide and water
oxygen and carbon

Answer and explanation

carbon dioxide and water

Complete combustion of a hydrocarbon (fuel + O₂) always yields carbon dioxide and water.

Problem 5

Solid calcium oxide (CaO) reacts with water. Predict the product, name the reaction type, and give the balanced equation.

Answer and explanation

It is a synthesis reaction: calcium oxide combines with water to form calcium hydroxide, Ca(OH)₂. The balanced equation is CaO + H₂O → Ca(OH)₂.

Problem 6

In the activity series, a more reactive metal replaces a less reactive one. Which single-replacement reaction will actually occur?

Cu + ZnSO₄ → CuSO₄ + Zn (copper is less reactive than zinc)
2H₂O → 2H₂ + O₂
N₂ + 3H₂ → 2NH₃
Zn + CuSO₄ → ZnSO₄ + Cu (zinc is more reactive than copper)

Answer and explanation

Zn + CuSO₄ → ZnSO₄ + Cu (zinc is more reactive than copper)

Zinc sits above copper in the activity series, so zinc displaces copper — the reverse would not happen, and the other two are not single-replacement reactions.

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