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NCERT solutions Science Textbook for Class 10 chapter 1 Chemical Reactions and Equations

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Chapter 1 - Chemical Reactions and Equations

Page 6

Why should a magnesium ribbon be cleaned before it is burnt in air?

Q 1 | Page 6 | view solution

Write the balanced equation for the following chemical reactions

(i) Hydrogen + Chlorine → Hydrogen chloride
(ii) Barium chloride + Aluminium sulphate → Barium sulphate + Aluminium chloride
(iii) Sodium + Water → Sodium hydroxide + Hydrogen

Q 2 | Page 6 | view solution

Write a balanced chemical equation with state symbols for the following reactions.

(i) Solutions of barium chloride and sodium sulphate in water react to give insoluble barium sulphate and the solution of sodium chloride.

(ii) Sodium hydroxide solution (in water) reacts with hydrochloric acid solution (in water) to produce sodium chloride solution and water.

Q 3 | Page 6 | view solution

Page 10

A solution of a substance ‘X’ is used for white washing.
(i) Name the substance ‘X’ and write its formula.
(ii) Write the reaction of the substance ‘X’ named in (i) above with water.

Q 1 | Page 10 | view solution

Why is the amount of gas collected in one of the test tubes in Activity 1.7 double of the amount collected in the other? Name this gas.

Q 2 | Page 10 | view solution

Page 13

Why does the colour of copper sulphate solution change when an iron nail is dipped in it?

Q 1 | Page 13 | view solution

Give an example of a double displacement reaction other than the one given in Activity.

Q 2 | Page 13 | view solution

Identify the substances that are oxidised and the substances that are reduced in the following reactions.

(i) 4Na (s) + O2 (g) → 2Na2O (s)

(ii) CuO (s) + H2 (g) → Cu (s) + H2O (l)

Q 3 | Page 13 | view solution

Pages 14 - 16

1. Which of the statements about the reaction below are incorrect?
2PbO (s) + C (s) → 2Pb (s) + CO2 (g)
(a) Lead is getting reduced.
(b) Carbon dioxide is getting oxidised.
(c) Carbon is getting oxidised.
(d) Lead oxide is getting reduced.

(i) (a) and (b)
(ii) (a) and (c)
(iii) (a), (b) and (c)
(iv) all

Q 1 | Page 14 | view solution

Fe2O3 + 2Al → Al2O3 + 2Fe
The above reaction is an example of a
(a) combination reaction.
(b) double displacement reaction.
(c) decomposition reaction.
(d) displacement reaction.

Q 2 | Page 14 | view solution

 What happens when dilute hydrochloric acid is added to iron fillings? Tick the correct answer.

  1. Hydrogen gas and Iron chloride are produced.
  2. Chlorine gas and Iron hydroxide are produced.
  3. No reaction takes place.
  4. Iron salt and water are produced.
Q 3 | Page 15 | view solution

What is a balanced chemical equation? Why should a chemical equation be balanced?

Q 4 | Page 15 | view solution

 Translate the following statements into chemical equations and then balance them.

  •  Hydrogen gas combines with nitrogen to form ammonia
Q 5.1 | Page 15 | view solution

Translate the following statements into chemical equations and then balance them.

  •  Hydrogen sulphide gas burns in air to give water and sulphur dioxide.
Q 5.2 | Page 15 | view solution

Translate the following statements into chemical equations and then balance them.

  • Barium chloride reacts with aluminium sulphate to give aluminium chloride and a precipitate of barium sulphate.
Q 5.3 | Page 15 | view solution

Translate the following statements into chemical equations and then balance them.

  • Potassium metal reacts with water to give potassium hydroxide and hydrogen gas
Q 5.4 | Page 15 | view solution

Balance the chemical equations.

HNO3+Ca(OH)2Ca(NO3)2+H2O

Q 6.1 | Page 15 | view solution

 Balance the following chemical equations.

 NaOH+H2SO4Na2SO4+H2O

Q 6.2 | Page 15 | view solution

 Balance the following chemical equations.

 NaCl+AgNO3AgCl+NaNO3

Q 6.3 | Page 15 | view solution

Balance the following chemical equations.

BaCl2 + H2SO4 → BaSO4 + HCl

Q 6.4 | Page 15 | view solution

Write the balanced chemical equations for the following reactions.

Barium chloride + Potassium sulphate → Barium sulphate + Potassium chloride

Q 7.1 | Page 15 | view solution

Write the balanced chemical equations for the following reactions.

Aluminium + Copper chloride → Aluminium chloride + Copper

Q 7.2 | Page 15 | view solution

Write the balanced chemical equations for the following reactions.

Zinc + Silver nitrate → Zinc nitrate + Silver

Q 7.3 | Page 15 | view solution

Write the balanced chemical equations for the following reactions.

Calcium hydroxide + Carbon dioxide → Calcium carbonate + Water

Q 7.4 | Page 15 | view solution

Write the balanced chemical equation for the following and identify the type of reaction 

Potassium bromide (aq) + Barium iodide (aq) → Potassium iodide (aq) + Barium bromide(s)

Q 8.1 | Page 15 | view solution

Write the balanced chemical equation for the following and identify the type of reaction

Zinc carbonate (s) → Zinc oxide (s) + Carbon dioxide (g)

Q 8.2 | Page 15 | view solution

Write the balanced chemical equation for the following and identify the type of reaction

Hydrogen (g) + Chlorine (g) → Hydrogen chloride (g)

Q 8.3 | Page 15 | view solution

Write the balanced chemical equation for the following and identify the type of reaction 

Magnesium (s) + Hydrochloric acid (aq) → Magnesium chloride (aq) + Hydrogen (g)

Q 8.4 | Page 15 | view solution

What does one mean by exothermic and endothermic reactions? Give examples.

Q 9 | Page 15 | view solution

 Why is respiration considered an exothermic reaction? Explain.

Q 10 | Page 15 | view solution

Why are decomposition reactions called the opposite of combination reactions? Write equations for these reactions.

Q 11 | Page 15 | view solution

 Write one equation each for decomposition reactions where energy is supplied in the form of heat, light or electricity.

Q 12 | Page 16 | view solution

What is the difference between displacement and double displacement reactions? Write equations for these reactions.

Q 13 | Page 16 | view solution

In the refining of silver, the recovery of silver from silver nitrate solution involved displacement by copper metal. Write down the reaction involved.

Q 14 | Page 16 | view solution

What do you mean by a precipitation reaction? Explain by giving examples.

Q 15 | Page 16 | view solution

 A shiny brown-coloured element ‘X’ on heating in air becomes black in colour. Name the element ‘X’ and the black coloured compound formed

Q 17 | Page 16 | view solution

Why do we apply paint on iron articles?

Q 18 | Page 16 | view solution

Oil and Fat containing food items are flushed with Nitrogen. Why?

Q 19 | Page 16 | view solution

 Explain the terms Corrosion

Q 20.1 | Page 16 | view solution

Explain the terms Rancidity

Q 20.2 | Page 16 | view solution

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