Class 9 Chemistry · Chapter 5 · Test 9

Mixed Conceptual Problems

25 MCQs covering systems and surroundings, enthalpy, exothermic and endothermic reactions, bond energies, activation energy, catalysts, reaction profiles, and biological energy.

MCQs

25 questions · 20 min · 25 marks

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Sample questions

The first 5 of 25. Try each one, then tap to see the answer.

Question 1
The part of the universe being studied in a chemical reaction is called the:
- ASurroundings
- BSystem
- CCatalyst
- DTransition state
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Answer: B
The system is the part being studied while everything else is the surroundings.
Question 2
Everything outside the system is called the:
- AReactants
- BProducts
- CSurroundings
- DChemical system
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Answer: C
The surroundings include everything outside the system being studied.
Question 3
At constant pressure what does the enthalpy change of a reaction equal?
- AThe mass of reactants
- BThe heat evolved or absorbed
- CThe activation energy only
- DThe volume of products
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Answer: B
At constant pressure ΔH equals the heat evolved or absorbed by the system.
Question 4
Which sign of ΔH represents an exothermic reaction?
- APositive
- BNegative
- CZero
- DUndefined
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Answer: B
An exothermic reaction releases energy and has a negative ΔH.
Question 5
Which sign of ΔH represents an endothermic reaction?
- APositive
- BNegative
- CZero
- DAlways negative
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Answer: A
An endothermic reaction absorbs energy and has a positive ΔH.

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