Chemistry – Chemical Reactions

1. Which of the following equations describes the reaction between Calcium oxide and water to produce Slaked lime?

  1. CaO + H2O → Ca(OH)2
  2. NaCl + H2O → NaOH
  3. HCl + NaOH → NaCl + H2O
  4. Fe2O3 + H2O → Fe(OH)3
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Answer: Option A. CaO + H2O → Ca(OH)2

2. Which of the following is an example of a chemical change?

  1. Rusting of iron
  2. Boiling water
  3. Mixing salt in water
  4. Breaking a glass
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Answer: Option A. Rusting of iron

3. Which of the following refers to an endothermic reaction?

  1. Reaction of Water and Calcium Chloride
  2. Reaction of Water and Nitric acid
  3. Rusting of iron
  4. Decomposition of calcium carbonate results in calcium oxide and carbon dioxide
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Answer: Option D. Decomposition of calcium carbonate results in calcium oxide and carbon dioxide

4. What is the reaction in which heat is produced called?

  1. Endothermic reactions
  2. Exothermic reactions
  3. Neutral reactions
  4. Reversible reactions
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Answer: Option B. Exothermic reactions

5. Which of the following occurs in oxidation reactions?

  1. Gain of electrons
  2. No change in the electron count
  3. Increase in mass
  4. Loss of electrons
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Answer: Option D. Loss of electrons