NCERT Class X Science Class: Chapter –1. Chemical Reactions and Equations – Part-5

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Question 21:

Complete the missing components/variables given as x and y in the following reactions

Answer:

Question 22:

Which among the following changes are exothermic or endothermic in nature?

  1. Decomposition of ferrous sulphate

  2. Dilution of sulphuric acid

  3. Dissolution of sodium hydroxide in water

  4. Dissolution of ammonium chloride in water

Answer:

(B) and (C) are exothermic as heat is released in these changes.

(A) and (D) are endothermic as heat is absorbed in these changes

Question 23:

Identify the reducing agent in the following reactions

Answer:

  1. gets oxidized to NO (Removal of hydrogen, addition of oxygen) gets reduced to ( Addition of hydrogen).

    Thus, Ammonia acts as reducing agent.

  2. gets reduced to (Addition of hydrogen) gets oxidized to (Removal of hydrogen)

    Hence, acts as reducing agent.

  3. gets reduced to (Removal of oxygen) gets oxidized to (Addition of oxygen)

    Hence, acts as reducing agent.

  4. gets oxidized to (Addition of oxygen) gets reduced to (Addition of hydrogen)

    Hence, acts as reducing agent.

Question 24:

Identify the oxidising agent (oxidant) in the following reactions

Answer:

Question 25:

Write the balanced chemical equations for the following reactions

  1. Sodium carbonate on reaction with hydrochloric acid in equal molar concentrations gives sodium chloride and sodium hydrogen carbonate.

  2. Sodium hydrogen carbonate on reaction with hydrochloric acid gives sodium chloride, water and liberates carbon dioxide.

  3. Copper sulphate on treatment with potassium iodide precipitates cuprous iodide , liberates iodine gas and also forms potassium sulphate.

Answer: