Practise 53 real Federal Board questions on Chemical Reactivity from 2023 to 2026. See the answer and explanation as soon as you answer.
Chemical Reactivity is one of the 11 main chapters in our Federal Board Matric Chemistry question bank (9th class), and about 15% of its real questions come from it. Tayyari Karo has 53 real questions on this chapter from 2023 to 2026; 16 are multiple choice and marked instantly, and the rest are short and long questions with a model answer. By difficulty: 31 medium, 22 easy.
Work through the questions below, then open the explanation for each one. Redo the ones you missed a few days later.
These are real past-paper questions. Think of your answer first, then open the explanation.
The sum of oxidation numbers of all atoms in a sulfate ion (SO₄²⁻) must be:
Answer: A. −2
For any polyatomic ion, the sum of oxidation numbers of its atoms equals the overall charge on the ion, which here is −2.
For a reversible reaction, why might the reaction not go to completion?
Answer: C. Backward reaction occurs simultaneously
In a reversible reaction, as soon as products form they start reacting backward to reform reactants, so the reaction reaches equilibrium rather than going to 100% completion.
An alkane is most likely to undergo:
Answer: D. Substitution reaction
Alkanes are saturated (no double/triple bonds), so they cannot undergo addition; instead they typically undergo substitution reactions (e.g. halogenation) under suitable conditions like UV light.
Which acid disintegrates marble buildings by forming acid rain?
Answer: A. H₂SO₄
Sulfuric acid (H₂SO₄, formed from SO₂ pollutants) is a major component of acid rain that reacts with and erodes marble (CaCO₃) buildings.
Catalytic converters help in controlling the emission of:
Answer: C. CO, NO
Catalytic converters in vehicles convert harmful CO and NO (and unburnt hydrocarbons) into less harmful CO₂, N₂ and H₂O.
Which hydrogen halide is most reactive?
Answer: D. HI
Bond strength H–X decreases down the group (HF strongest, HI weakest), so HI breaks most easily and is the most reactive hydrogen halide.
Briefly describe: (a) How a catalyst affects the reaction rate? (b) How a catalyst affects the activation energy?
(a) A catalyst increases the rate of a chemical reaction without itself being permanently consumed, by providing an alternative reaction pathway.
(b) A catalyst lowers the activation energy required for the reaction, allowing a greater fraction of reactant molecules to have sufficient energy to react at a given temperature, thereby speeding up the reaction.
Explain the following methods of prevention of corrosion: (a) Sacrificial protection (b) Galvanizing
(a) Sacrificial protection: A more reactive metal (such as zinc or magnesium) is attached to the metal (e.g. iron) that needs protection. The more reactive metal corrodes/oxidizes preferentially (loses electrons more readily), 'sacrificing' itself to protect the less reactive metal from corrosion, since it acts as the anode in the resulting electrochemical setup while iron stays protected as the cathode.
(b) Galvanizing: Iron or steel objects are coated with a thin layer of zinc (by dipping in molten zinc or electroplating). …
The full model answer is in the app.
| Session | Questions |
|---|---|
| 2026 Annual | 12 |
| 2025 1st Annual | 16 |
| 2025 2nd Annual | 12 |
| 2024 Annual | 7 |
| 2023 Annual | 6 |
53 real Federal Board (FBISE) Chemistry questions on Chemical Reactivity from 2023 to 2026, for 9th class. Each one shows the session it came from.
No. We could not find an official FBISE marking scheme for these papers, so the answers and explanations are written by Tayyari Karo for practice. Check anything important with your teacher or textbook.
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