Which of the following is a chemical change?
Combustion of petrol
Correct Answer: Combustion of petrol
A chemical change produces new substances with different properties and is generally irreversible.
- Combustion of petrol: C₈H₁₈ + O₂ → CO₂ + H₂O + energy → chemical change ✓
- Mixing salt and water → physical change (can be recovered by evaporation)
- Evaporation of water → physical change (state change only)
- Ice melting → physical change (state change; water is still H₂O)
Signs of chemical change: new substance formed, energy change, colour/smell change, gas/precipitate produced.
Similar Questions
If a piece of aluminium is added to iron(II) sulphate (FeSO4) solution, what will happen?
Balance the following reaction:
\(3\,\text{MnO}_2\,(s) + x\,\text{Al}\,(s) \rightarrow 3\,\text{Mn}\,(l) + y\,\text{Al}_2\text{O}_3\,(s) + \text{Heat}\)
What is the primary chemistry behind a displacement reaction?
What type of ions exchange between reactants in a double displacement reaction?
What is the primary purpose of anodising aluminium?
What is generally produced when a metal reacts with an acid?
Important Questions from Chemical Reaction
- Which one of the following is not an example of a redox reaction?
- Which one of the following is not a pigment?
- Which one of the following reactions is an example of decomposition reaction?
Match List I with List II and select the correct answer using the code given below the Lists:
LIST I
(Chemical process)
LIST II
(Reaction)
A.
Electrolysis of water
1.
Double displacement
reactionB.
Burning of coal
2.
Combination reaction
C.
Iron nail immersed in copper sulphate solution
3.
Decomposition reaction
D.
Addition of barium chloride solution to aluminium sulphate solution
4.
Displacement reaction
Consider the following reaction:
Fe2O3(s) + 2Al(s) → 2Fe(s) + Al2O3(s)
Which of the following statements about the given reaction is NOT correct?
