Class X Chapter 1 – Chemical Reactions and Equations Science
Question 1:
Why should a magnesium ribbon be cleaned before burning in air?
Answer
Magnesium is very reactive metal. When stored it reacts with oxygen to form a layer
magnesium oxide on its surface. This layer of magnesium oxide is quite stable and
prevents further reaction of magnesium with oxygen. The magnesium ribbon is cleaned
by sand paper to remove this layer so that the underlying metal can be exposed into air.
Question 2:
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
Answer
(i)
(ii)
(iii)
Question 3:
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.
Answer
(i)
(ii)
Page 1 of 13
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, Class X Chapter 1 – Chemical Reactions and Equations Science
Question 1:
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.
Answer
(i) The substance ‘X’ is calcium oxide. Its chemical formula is CaO.
(ii) Calcium oxide reacts vigorously with water to form calcium hydroxide (slaked lime).
Question 2:
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.
Answer
Water (H2O) contains two parts hydrogen and one part oxygen. Therefore, the amount of
hydrogen and oxygen produced during electrolysis of water is in a 2:1 ratio. During
electrolysis, since hydrogen goes to one test tube and oxygen goes to another, the
amount of gas collected in one of the test tubes is double of the amount collected in the
other.
Page 2 of 13
Website: www.vidhyarjan.com Email: Mobile: 9999 249717
Head Office: 1/3-H-A-2, Street # 6, East Azad Nagar, Delhi-110051
(One Km from ‘Welcome Metro Station)
Question 1:
Why should a magnesium ribbon be cleaned before burning in air?
Answer
Magnesium is very reactive metal. When stored it reacts with oxygen to form a layer
magnesium oxide on its surface. This layer of magnesium oxide is quite stable and
prevents further reaction of magnesium with oxygen. The magnesium ribbon is cleaned
by sand paper to remove this layer so that the underlying metal can be exposed into air.
Question 2:
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
Answer
(i)
(ii)
(iii)
Question 3:
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.
Answer
(i)
(ii)
Page 1 of 13
Website: www.vidhyarjan.com Email: Mobile: 9999 249717
Head Office: 1/3-H-A-2, Street # 6, East Azad Nagar, Delhi-110051
(One Km from ‘Welcome Metro Station)
, Class X Chapter 1 – Chemical Reactions and Equations Science
Question 1:
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.
Answer
(i) The substance ‘X’ is calcium oxide. Its chemical formula is CaO.
(ii) Calcium oxide reacts vigorously with water to form calcium hydroxide (slaked lime).
Question 2:
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.
Answer
Water (H2O) contains two parts hydrogen and one part oxygen. Therefore, the amount of
hydrogen and oxygen produced during electrolysis of water is in a 2:1 ratio. During
electrolysis, since hydrogen goes to one test tube and oxygen goes to another, the
amount of gas collected in one of the test tubes is double of the amount collected in the
other.
Page 2 of 13
Website: www.vidhyarjan.com Email: Mobile: 9999 249717
Head Office: 1/3-H-A-2, Street # 6, East Azad Nagar, Delhi-110051
(One Km from ‘Welcome Metro Station)
