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ICSE Class 9 Chemical Changes and Reactions — practice questions

Explore 28 free Chemical Changes and Reactions questions in ICSE Class 9 Chemistry. Open each question or exercise to read its content, reference answers and available explanation.

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Chemical Changes and Reactions questions and exercises with answers

Showing questions 1–28 of 28.

In thermochemistry, an exothermic reaction has an enthalpy change that is:Read the answer and worked solution →An endothermic reaction is characterized as a process that:Read the answer and worked solution →An endothermic process typically affects the surrounding temperature by:Read the answer and worked solution →A reaction is exothermic when the energy of newly formed bonds is:Read the answer and worked solution →A reaction where two simple substances combine into a complex compound is:Read the answer and worked solution →When a chemical compound splits into two or more simpler substances, it is:Read the answer and worked solution →When an uncombined element replaces an element in a compound, it is a:Read the answer and worked solution →When anions and cations of two reacting compounds mutually switch places:Read the answer and worked solution →A catalyst speeds up a chemical reaction primarily by:Read the answer and worked solution →Chemical substances that slow down the speed of a reaction are called:Read the answer and worked solution →Substances that increase the activity of catalysts are known as:Read the answer and worked solution →Substances that deactivate or destroy the efficiency of a catalyst are:Read the answer and worked solution →In a chemical equation, which symbol represents a reversible reaction?Read the answer and worked solution →In modern chemistry, oxidation of an atom is defined by a:Read the answer and worked solution →What change in oxidation state signifies that chemical reduction occurred?Read the answer and worked solution →In a redox process, the chemical species that donates electrons is the:Read the answer and worked solution →Which reactant acts as the electron acceptor in a redox reaction pair?Read the answer and worked solution →Which type of chemical change is driven by the absorption of light photons?Read the answer and worked solution →In heterolytic bond fission, both electrons of the broken bond remain with:Read the answer and worked solution →The combustion of hydrocarbon fuels like natural gas is an example of an:Read the answer and worked solution →The term endothermic was coined by which nineteenth-century chemist?Read the answer and worked solution →Dissolving ammonium nitrate salt in water is a classic example of an:Read the answer and worked solution →Chemical equilibrium in a reversible reaction is reached when:Read the answer and worked solution →A catalyst that exists in a different physical phase from reactants is:Read the answer and worked solution →Match each reaction classification with its hallmark characteristic:Read the answer and worked solution →Match each catalyst type with its operational effect on reactions:Read the answer and worked solution →Match each oxidation-reduction term with its electronic definition:Read the answer and worked solution →Match each observable reaction indicator with the chemical phenomenon:Read the answer and worked solution →

Worked practice questions

In thermochemistry, an exothermic reaction has an enthalpy change that is:

  1. Strictly negative
  2. Strictly positive
  3. Always equal to zero
  4. Infinite in magnitude
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Correct answer: A. Strictly negative

An exothermic reaction releases energy to its surroundings, resulting in a negative enthalpy change.

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An endothermic reaction is characterized as a process that:

  1. Emits visible light
  2. Absorbs heat energy
  3. Destroys thermal heat
  4. Releases excess sound
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Correct answer: B. Absorbs heat energy

Endothermic reactions absorb thermal energy directly from the surrounding environment.

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An endothermic process typically affects the surrounding temperature by:

  1. Doubling it rapidly
  2. Increasing it steadily
  3. Decreasing it notably
  4. Leaving it unaffected
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Correct answer: C. Decreasing it notably

Because heat is drawn into the reaction system, the temperature of the surrounding environment drops.

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More Chemistry topics

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