Page 20 - NCERT Science Class 10 English Medium

(c) decomposition reaction.
(d) displacement reaction.
3. What happens when dilute hydrochloric acid is added to iron fillings? Tick the
correct answer.
(a) Hydrogen gas and iron chloride are produced.
(b) Chlorine gas and iron hydroxide are produced.
(c) No reaction takes place.
(d) Iron salt and water are produced.
4. What is a balanced chemical equation? Why should chemical equations be
balanced?
5. Translate the following statements into chemical equations and then balance them.
(a) Hydrogen gas combines with nitrogen to form ammonia.
(b) Hydrogen sulphide gas burns in air to give water and sulpur dioxide.
(c) Barium chloride reacts with aluminium sulphate to give aluminium chloride
and a precipitate of barium sulphate.
(d) Potassium metal reacts with water to give potassium hydroxide and hydrogen
gas.
6. Balance the following chemical equations.
(a) HNO +Ca(OH) → Ca(NO ) + H O
3 2 3 2 2
(b) NaOH + H SO → Na SO + H O
2 4 2 4 2
(c) NaCl + AgNO → AgCl + NaNO
3 3
(d) BaCl + H SO → BaSO + HCl
2 2 4 4
7. Write the balanced chemical equations for the following reactions.
(a) Calcium hydroxide + Carbon dioxide → Calcium carbonate + Water
(b) Zinc + Silver nitrate → Zinc nitrate + Silver
(c) Aluminium + Copper chloride → Aluminium chloride + Copper
(d) Barium chloride + Potassium sulphate → Barium sulphate + Potassium chloride
8. Write the balanced chemical equation for the following and identify the type of
reaction in each case.
(a) Potassium bromide(aq) + Barium iodide(aq) → Potassium iodide(aq) +
Barium bromide(s)
(b) Zinc carbonate(s) → Zinc oxide(s) + Carbon dioxide(g)
(c) Hydrogen(g) + Chlorine(g) → Hydrogen chloride(g)
(d) Magnesium(s) + Hydrochloric acid(aq) → Magnesium chloride(aq) + Hydrogen(g)
9. What does one mean by exothermic and endothermic reactions? Give examples.
10. Why is respiration considered an exothermic reaction? Explain.
11. Why are decomposition reactions called the opposite of combination reactions?
Write equations for these reactions.

Chemical Reactions and Equations 15

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