Chapter 1
Chemical Reactions And Equations
ā§°াāϏাāϝ়āύিāĻ āĻĒ্ā§°āϤিāĻ্ā§°িāϝ়া āĻā§°ু āϏāĻŽীāĻā§°āĻŖ
EXERCISES
āĻŦ্āϝাāϝ়াāĻŽ
1. āϤāϞ⧰ āĻĒ্ā§°āϤিāĻ্ā§°িāϝ়াā§° āĻŦিāώāϝ়ে āĻোāύāĻো āĻŽāύ্āϤāĻŦ্āϝ āĻ āĻļুāĻĻ্āϧ?
2PbO(s) + C(s) → 2Pb(s) + CO2(g)
2āĻĒিāĻŦিāĻ(āĻŦোā§°) + āĻি(āĻŦোā§°) → 2āĻĒিāĻŦি(āĻŦোā§°) + āĻি.āĻ.2(āĻি)
(āĻ) āϏীāĻš āĻš্ā§°াāϏ āĻšৈ āĻāĻšিāĻে।
(b) Carbon dioxide is getting oxidised.
(āĻ) āĻাā§°্āĻŦāύ āĻĄাāĻ āĻ āĻ্āϏাāĻāĻĄ āĻাā§°āĻŖ āĻšৈ āĻāĻে।
(c) Carbon is getting oxidised.
(āĻ) āĻাā§°্āĻŦāύ āĻ āĻ্āϏিāĻĄাāĻāĻ āĻšৈ āĻāĻে।
(d) Lead oxide is getting reduced.
(āĻ) āϞীāĻĄ āĻ āĻ্āϏাāĻāĻĄ āĻš্ā§°াāϏ āĻšৈ āĻāĻšিāĻে।
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(i) (a) and (b)
āĻ) (āĻ) āĻā§°ু (āĻ)
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(ii) (a) and (c)
(āĻ) (āĻ) āĻā§°ু (āĻ)
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(iii) (a), (b) and (c)
(āĻ) (āĻ), (āĻ) āĻā§°ু (āĻ)
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(iv) all
(āĻ) āϏāĻāϞো
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2. Fe,O,+2A1 → Al,0, + 2Fe
2. āĻĢে, āĻ,+2āĻ1 → āĻāϞ,0, + 2āĻĢে
āĻāĻĒā§°োāĻ্āϤ āĻĒ্ā§°āϤিāĻ্ā§°িāϝ়াāĻো āĻāĻা ā§° āĻāĻĻাāĻšā§°āĻŖ
(āĻ) āϏংāĻŽিāĻļ্ā§°āĻŖ āĻĒ্ā§°āϤিāĻ্ā§°িāϝ়া।
(b) double displacement reaction.
(āĻ) āĻĻ্āĻŦৈāϤ āϏ্āĻĨাāύāĻ্āϝুāϤি āĻĒ্ā§°āϤিāĻ্ā§°িāϝ়া।
(c) decomposition reaction.
(āĻ) āĻĒāĻāύ āĻĒ্ā§°āϤিāĻ্ā§°িāϝ়া।
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(d) displacement reaction.
(āĻ) āϏ্āĻĨাāύāĻ্āϝুāϤি āĻĒ্ā§°āϤিāĻ্ā§°িāϝ়া।
3. What happens when dilute hydrochloric acid is added to iron fillings? Tick the correct answer. (a) Hydrogen gas and iron chloride are produced.
3. āϞোā§° āĻā§°্āϤিāϤ āĻĒাāϤāϞ āĻšাāĻāĻĄ্ā§°āĻ্āϞ'ā§°িāĻ āĻāĻিāĻĄ āϝোāĻ āĻā§°িāϞে āĻি āĻšāϝ়? āϏāĻ িāĻ āĻāϤ্āϤ⧰āĻো āĻিāĻ āĻā§°āĻ। (āĻ) āĻšাāĻāĻĄ্ā§°āĻেāύ āĻেāĻ āĻā§°ু āϞোā§° āĻ্āϞ⧰াāĻāĻĄ āĻā§āĻĒāύ্āύ āĻšāϝ়।
(b) Chlorine gas and iron hydroxide are produced.
(āĻ) āĻ্āϞোā§°িāύ āĻেāĻ āĻā§°ু āϞোāĻšাāĻāĻĄ্ā§°āĻ্āϏাāĻāĻĄ āĻā§āĻĒাāĻĻāύ āĻā§°া āĻšāϝ়।
(c) No reaction takes place.
(āĻ) āĻোāύো āĻĒ্ā§°āϤিāĻ্ā§°িāϝ়া āύāĻšāϝ়।
(d) Iron salt and water are produced.
(āĻ) āϞো āύিāĻŽāĻ āĻā§°ু āĻĒাāύী āĻā§āĻĒাāĻĻāύ āĻā§°া āĻšāϝ়।
4. What is a balanced chemical equation? Why should chemical equations be balanced?
4. āĻāĻ āϏāύ্āϤুāϞিāϤ ā§°াāϏাāϝ়āύিāĻ āϏāĻŽীāĻā§°āĻŖ āĻি? ā§°াāϏাāϝ়āύিāĻ āϏāĻŽীāĻā§°āĻŖāĻŦোā§° āĻিāϝ় āϏāύ্āϤুāϞিāϤ āĻā§°িāĻŦ āϞাāĻে?
5. Translate the following statements into chemical equations and then balance them.
5. āύিāĻŽ্āύāϞিāĻিāϤ āĻŽāύ্āϤāĻŦ্āϝāĻŦোā§° ā§°াāϏাāϝ়āύিāĻ āϏāĻŽীāĻā§°āĻŖāϞৈ āĻ āύুāĻŦাāĻĻ āĻā§°āĻ āĻā§°ু āϤাā§° āĻĒিāĻāϤ āϏেāĻāĻŦোā§° āϏāύ্āϤুāϞিāϤ āĻā§°āĻ।
(a) Hydrogen gas combines with nitrogen to form ammonia.
(āĻ) āĻšাāĻāĻĄ্ā§°āĻেāύ āĻেāĻ āύাāĻāĻ্ā§°āĻেāύ⧰ āϏৈāϤে āĻŽিāĻšāϞি āĻšৈ āĻāĻŽোāύিāϝ়া āĻāĻ āύ āĻā§°ে।
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(b) Hydrogen sulphide gas burns in air to give water and sulpur dioxide.
(āĻ) āĻĒাāύী āĻā§°ু āĻাāϞāĻĒুā§° āĻĄাāĻ āĻ āĻ্āϏাāĻāĻĄ āĻĻিāĻŦāϞৈ āĻšাāĻāĻĄ্ā§°āĻেāύ āĻাāϞāĻĢাāĻāĻĄ āĻেāĻ āĻŦাāϝ়ুāϤ āĻ্āĻŦāϞে।
(c) Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate.
(āĻ) āĻŦেā§°িāϝ়াāĻŽ āĻ্āϞ⧰াāĻāĻĄে āĻāϞুāĻŽিāύিāϝ়াāĻŽ āĻাāϞāĻĢেāĻā§° āϏৈāϤে āĻĒ্ā§°āϤিāĻ্ā§°িāϝ়া āĻā§°ি āĻāϞুāĻŽিāύিāϝ়াāĻŽ āĻ্āϞ⧰াāĻāĻĄ āĻā§°ু āĻŦেā§°িāϝ়াāĻŽ āĻাāϞāĻĢেāĻā§° āĻ ā§ąāĻ্āώāϝ় āĻĒ্ā§°āĻĻাāύ āĻā§°ে।
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(d) Potassium metal reacts with water to give potassium hydroxide and hydrogen gas.
(āĻ) āĻĒāĻাāĻিāϝ়াāĻŽ āϧাāϤুāĻ āĻĒাāύীā§° āϏৈāϤে āĻŦিāĻ্ā§°িāϝ়া āĻā§°ি āĻĒāĻাāĻিāϝ়াāĻŽ āĻšাāĻāĻĄ্ā§°āĻ্āϏাāĻāĻĄ āĻā§°ু āĻšাāĻāĻĄ্ā§°āĻেāύ āĻেāĻ āĻĒ্ā§°āĻĻাāύ āĻā§°ে।
6. Balance the following chemical equations.
6. āύিāĻŽ্āύāϞিāĻিāϤ ā§°াāϏাāϝ়āύিāĻ āϏāĻŽীāĻā§°āĻŖāĻŦোā§° āϏāύ্āϤুāϞিāϤ āĻā§°āĻ।
(āĻ) āĻāĻāĻāĻāύāĻ, +āĻে(āĻāĻāĻāĻ), → āĻে(āĻāύāĻ3)2 + āĻāĻāĻ₂āĻ
(b) NaOH + H₂SO,→ Na₂SO, +H₂O (c) NaCl + AgNO,→ AgCl + NaNO,
(āĻ) āύাāĻāĻš + āĻāĻāĻ₂āĻāĻāĻ,→ āύা₂āĻāĻāĻ, +āĻāĻāĻ₂āĻ (āĻ) āĻāύāĻāĻিāĻāϞ + āĻāĻিāĻāύāĻ ', → āĻāĻিāĻিāĻāϞ + āύাāύো,
(d) BaCl2 + H₂SO → BaSO, + HCl
(āĻ) āĻŦিāĻāĻিāĻāϞ2 + āĻāĻāĻ₂āĻāĻāĻ ' → āĻŦিāĻāĻāĻāĻ, + āĻāĻāĻāĻিāĻāϞ
7. Write the balanced chemical equations for the following reactions.
7. āύিāĻŽ্āύāϞিāĻিāϤ āĻĒ্ā§°āϤিāĻ্ā§°িāϝ়াāĻŦোā§°ā§° āĻŦাāĻŦে āϏāύ্āϤুāϞিāϤ ā§°াāϏাāϝ়āύিāĻ āϏāĻŽীāĻā§°āĻŖāĻŦোā§° āϞিāĻāĻ।
(āĻ) āĻেāϞāĻিāϝ়াāĻŽ āĻšাāĻāĻĄ্ā§°āĻ্āϏাāĻāĻĄ + āĻাā§°্āĻŦāύ āĻĄাāĻ āĻ āĻ্āϏাāĻāĻĄ → āĻেāϞāĻিāϝ়াāĻŽ āĻাā§°্āĻŦāύেāĻ + āĻĒাāύী
(b) Zinc+ Silver nitrate → Zinc nitrate + Silver
(āĻ) āĻিংāĻ+ āĻিāϞāĻাā§° āύাāĻāĻ্ā§°েāĻ → āĻিংāĻ āύাāĻāĻ্ā§°েāĻ + ā§°ূāĻĒাāϞী
(c) Aluminium + Copper chloride → Aluminium chloride + Copper
(āĻ) āĻāϞুāĻŽিāύিāϝ়াāĻŽ + āĻāĻĒাā§° āĻ্āϞ⧰াāĻāĻĄ → āĻāϞুāĻŽিāύিāϝ়াāĻŽ āĻ্āϞ⧰াāĻāĻĄ + āϤাāĻŽ
(d) Barium chloride + Potassium sulphate→ Barium sulphate + Potassium chloride
(āĻ) āĻŦেā§°িāϝ়াāĻŽ āĻ্āϞ⧰াāĻāĻĄ + āĻĒāĻাāĻিāϝ়াāĻŽ āĻাāϞāĻĢেāĻ→ āĻŦেā§°িāϝ়াāĻŽ āĻাāϞāĻĢেāĻ + āĻĒāĻাāĻিāϝ়াāĻŽ āĻ্āϞ⧰াāĻāĻĄ
8. Write the balanced chemical equation for the following and identify the type of reaction in each case.
8. āύিāĻŽ্āύāϞিāĻিāϤāĻŦোā§°ā§° āĻŦাāĻŦে āϏāύ্āϤুāϞিāϤ ā§°াāϏাāϝ়āύিāĻ āϏāĻŽীāĻā§°āĻŖ āϞিāĻāĻ āĻā§°ু āĻĒ্ā§°āϤিāĻো āĻ্āώেāϤ্ā§°āϤ āĻĒ্ā§°āϤিāĻ্ā§°িāϝ়াā§° āĻĒ্ā§°āĻাā§° āĻিāύাāĻ্āϤ āĻā§°āĻ।
(a) Potassium bromide(aq) + Barium iodide(aq) → Potassium iodide(aq) +
(āĻ) āĻĒāĻাāĻিāϝ়াāĻŽ āĻŦ্ā§°āĻŽাāĻāĻĄ (āĻāĻ) + āĻŦেā§°িāϝ়াāĻŽ āĻāϝ়োāĻĄাāĻāĻĄ (āĻāĻ) → āĻĒāĻাāĻিāϝ়াāĻŽ āĻāϝ়োāĻĄাāĻāĻĄ (āĻāĻ) + āĻŦেā§°িāϝ়াāĻŽ āĻŦ্ā§°āĻŽাāĻāĻĄ(āĻŦোā§°)
(b) Zinc carbonate(s) →→ Zinc oxide(s) + Carbon dioxide(g)
(āĻ) āĻিংāĻ āĻাā§°্āĻŦāύেāĻ(āĻŦোā§°) →→ āĻিংāĻ āĻ āĻ্āϏাāĻāĻĄ (āĻŦোā§°) + āĻাā§°্āĻŦāύ āĻĄাāĻ āĻ āĻ্āϏাāĻāĻĄ (āĻি)
(c) Hydrogen(g) + Chlorine(g) → Hydrogen chloride(g)
(āĻ) āĻšাāĻāĻĄ্ā§°āĻেāύ (āĻ্ā§°াāĻŽ) + āĻ্āϞোā§°িāύ (āĻ্ā§°াāĻŽ) → āĻšাāĻāĻĄ্ā§°āĻেāύ āĻ্āϞ⧰াāĻāĻĄ (āĻি)
(d) Magnesium(s) + Hydrochloric acid(aq) → Magnesium chloride(aq) + Hydrogen(g)
(āĻ) āĻŽেāĻāύেāĻিāϝ়াāĻŽ (āĻŦোā§°) + āĻšাāĻāĻĄ্ā§°āĻ্āϞ'ā§°িāĻ āĻāĻিāĻĄ (āĻāĻিāĻ) → āĻŽেāĻāύেāĻিāϝ়াāĻŽ āĻ্āϞ⧰াāĻāĻĄ (āĻāĻ) + āĻšাāĻāĻĄ্ā§°āĻেāύ(āĻি)
9. What does one mean by exothermic and endothermic reactions? Give examples.
9. āĻāĻ্āϏোāĻĨাā§°্āĻŽিāĻ āĻā§°ু āĻāĻŖ্āĻĄোāĻĨাā§°্āĻŽিāĻ āĻĒ্ā§°āϤিāĻ্ā§°িāϝ়াā§° āĻ ā§°্āĻĨ āĻি? āĻāĻĻাāĻšā§°āĻŖ āĻĻিāϝ়āĻ।
10. Why is respiration considered an exothermic reaction? Explain.
ā§§ā§Ļ. āĻļ্āĻŦāϏāύāĻ āĻিāϝ় āĻāĻ āĻāĻ্āĻৃংāĻāϞ āĻĒ্ā§°āϤিāĻ্ā§°িāϝ়া āĻŦুāϞি āĻāĻŖ্āϝ āĻā§°া āĻšāϝ়? āĻŦ্āϝাāĻ্āϝা āĻā§°āĻ।
11. Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions.
ā§§ā§§. āĻĒāĻāύ āĻĒ্ā§°āϤিāĻ্ā§°িāϝ়াāĻ āĻিāϝ় āϏংāĻŽিāĻļ্ā§°āĻŖ āĻĒ্ā§°āϤিāĻ্ā§°িāϝ়াā§° āĻŦিāĻĒā§°ীāϤ āĻŦুāϞি āĻোā§ąা āĻšāϝ়? āĻāĻ āĻĒ্ā§°āϤিāĻ্ā§°িāϝ়াāĻŦোā§°ā§° āĻŦাāĻŦে āϏāĻŽীāĻā§°āĻŖ āϞিāĻāĻ।
12. Write one equation each for decomposition reactions where energy is supplied in the form of heat, light or electricity.
12. āĻĒāĻāύ āĻĒ্ā§°āϤিāĻ্ā§°িāϝ়াā§° āĻŦাāĻŦে āĻāĻা āĻৈ āϏāĻŽীāĻā§°āĻŖ āϞিāĻāĻ āϝ'āϤ āϤাāĻĒ, āĻĒোāĻšā§° āĻŦা āĻŦিāĻĻ্āϝুāϤ⧰ ā§°ূāĻĒāϤ āĻļāĻ্āϤি āϝোāĻাāύ āϧ⧰া āĻšāϝ়।
13. What is the difference between displacement and double displacement reactions? Write equations for these reactions.
13. āϏ্āĻĨাāύāĻ্āϝুāϤি āĻā§°ু āĻĻ্āĻŦৈāϤ āϏ্āĻĨাāύাāύ্āϤ⧰ āĻĒ্ā§°āϤিāĻ্ā§°িāϝ়াā§° āĻŽাāĻāϤ āĻĒাā§°্āĻĨāĻ্āϝ āĻি? āĻāĻ āĻĒ্ā§°āϤিāĻ্ā§°িāϝ়াāĻŦোā§°ā§° āĻŦাāĻŦে āϏāĻŽীāĻā§°āĻŖ āϞিāĻāĻ।
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14. In the refining of silver, the recovery of silver from silver nitrate solution involved displacement by copper metal. Write down the reaction involved.
14. ā§°ূāĻĒā§° āĻļোāϧāύāϤ, ā§°ূāĻĒাāϞী āύাāĻāĻ্ā§°েāĻ āĻĻ্ā§°ā§ąāĻŖā§° āĻĒā§°া ā§°ূāĻĒ āĻĒুāύ⧰ুāĻĻ্āϧাā§°āϤ āϤাāĻŽāϧাāϤুā§° āĻĻ্āĻŦাā§°া āϏ্āĻĨাāύাāύ্āϤ⧰ āĻ āύ্āϤ⧰্āĻুāĻ্āϤ āĻāĻিāϞ। āĻ āύ্āϤ⧰্āĻুāĻ্āϤ āĻĒ্ā§°āϤিāĻ্ā§°িāϝ়াāĻো āϞিāĻāĻ।
15. What do you mean by a precipitation reaction? Explain by giving examples.
ā§§ā§Ģ. āĻŦā§°āώুāĻŖā§° āĻĒ্ā§°āϤিāĻ্ā§°িāϝ়াā§° āĻ ā§°্āĻĨ āĻি? āĻāĻĻাāĻšā§°āĻŖ āĻĻি āĻŦā§°্āĻŖāύা āĻā§°āĻ।
16. Explain the following in terms of gain or loss of oxygen with two examples each.
16. āĻĻুāĻা āĻৈ āĻāĻĻাāĻšā§°āĻŖā§° āϏৈāϤে āĻ āĻ্āϏিāĻেāύ āϞাāĻ āĻŦা āĻ্āώāϤিā§° āĻ্āώেāϤ্ā§°āϤ āύিāĻŽ্āύāϞিāĻিāϤāĻŦোā§° āĻŦā§°্āĻŖāύা āĻā§°āĻ।
(āĻ) āĻাā§°āĻŖ
(āĻ) āĻš্ā§°াāϏ
17. A shiny brown coloured element X on heating in air becomes black in colour. Name the element 'X' and the black coloured compound formed.
17. āĻŦāϤাāĻšāϤ āĻā§°āĻŽ āĻā§°াā§° āϏāĻŽāϝ়āϤ āĻāĻা āĻāĻāĻāĻে āĻŽুāĻা ā§°āĻā§° āĻāĻĒাāĻĻাāύ āĻāĻ্āϏ āĻ'āϞা ā§°āĻā§° āĻšৈ āĻĒā§°ে। 'āĻāĻ্āϏ' āĻāĻĒাāĻĻাāύāĻā§°ু āĻāĻ āύ āĻšোā§ąা āĻ'āϞা ā§°āĻā§° āϝৌāĻāĻোā§° āύাāĻŽ āĻĻিāϝ়āĻ।
18. Why do we apply paint on iron articles?
ā§§ā§Ž. āĻāĻŽি āϞোā§° āϏাāĻŽāĻ্ā§°ীā§° āĻāĻĒā§°āϤ ā§°ং āĻিāϝ় āĻĒ্ā§°āϝ়োāĻ āĻā§°োঁ?
19. Oil and fat containing food items are flushed with nitrogen. Why?
19. āĻাāĻĻ্āϝ āϏাāĻŽāĻ্ā§°ী āĻĨāĻা āϤেāϞ āĻā§°ু āĻā§°্āĻŦি āύাāĻāĻ্ā§°āĻেāύ⧰ āĻĻ্āĻŦাā§°া āĻĢ্āϞাāĻļ āĻā§°া āĻšāϝ়। āĻিāϝ়?
20. Explain the following terms with one example each.
20. āĻĒ্ā§°āϤিāĻো āĻāĻĻাāĻšā§°āĻŖেā§°ে āύিāĻŽ্āύāϞিāĻিāϤ āĻļāĻŦ্āĻĻāĻŦোā§° āĻŦā§°্āĻŖāύা āĻā§°āĻ।
(āĻ) āĻ্āώāϝ়
Ans-
(b) Rancidity
(āĻ) ā§°েāύāĻিāĻĄিāĻি