Properties Uses of Hydrogen Class-8th Goyal Brothers ICSE Chemistry Solutions Ch-7 Unit-2

Properties Uses of Hydrogen Class-8th Goyal Brothers ICSE Chemistry Solutions Ch-7 Unit-2. We Provide Step by Step Answers of Objectives, True and False, Incorrect and Correct , Definitions , Match the followings and Short/Long Question Type answers of Ch-7(Hydrogen) Unit-2(Properties and uses of Hydrogen). Visit official Website  CISCE  for detail information about ICSE Board Class-8

Properties Uses of Hydrogen Class-8th Goyal Brothers ICSE Chemistry Solutions Ch-7 Unit-2

Board	ICSE
Class	8th
Subject	Chemistry
Book Name	Goyal Brothers
Chapter-7	Hydrogen
Unit-2	Properties and uses of Hydrogen
Topic	Solution of exercise questions
Session	2023-24

OBJECTIVE TYPE QUESTIONS

Properties Uses of Hydrogen Class-8th Goyal Brothers ICSE Chemistry Solutions Ch-7 Unit-2

Que: A. Fill in the blank spaces by choosing the correct words from the given list :

List : Oxy-hydrogen, water, 14.4, combustible, hydrochloric acid.

1. Vapour density of hydrogen is 1, as compared to air being 14.4.

2. Hydrogen is a combustible gas, which does not support combustion.

3. Hydrogen reacts with chlorine to form hydrochloric acid gas.

4. Black copper oxide (heated) forms water and copper metal when hydrogen gas is passed over it.

5. The Oxy-hydrogen flame is used for cutting and welding purposes.

Que: B. Statements given below are incorrect. Write the correct statements :

Question: 1. Hydrogen gas is used in the manufacture of artificial fertilisers, such as potassium nitrate.

Answer: Hydrogen gas is used in the manufacture of artificial fertilisers, such as ammonium sulphate.

Question: 2. A mixture of hydrogen and chlorine, on exposure to direct sunlight, reacts quietly to form hydrochloric acid gas.

Answer: A mixture of hydrogen and chlorine, on exposure to direct sunlight, reacts explosively to form hydrochloric acid gas.

Question: 3. When a burning candle is taken inside the jar of chlorine, it burns with a bright flame.

Answer: When a burning candle is taken inside the jar of chlorine, it burns with a smoothy flame.

Question: 4. A shining silver mass is left behind when hydrogen gas is passed for long time over heated black copper oxide.

Answer: A shining blue mass is left behind when hydrogen gas is passed for long time over heated black copper oxide.

Question: 5. The product formed during the combustion of hydrogen in air is hydrogen peroxide.

Answer: The product formed during the combustion of hydrogen in air is hydrogen oxide.

Que: C. Match the statements in Column A, with those in Column B :

Column A	Column B
1. A substance which speeds up the rate of chemical reaction.	(a) Hydrochloric acid gas
2. A reaction in which hydrogen removes oxygen from heated metal oxides.	(b) Hydrogenation
3. The colour of flame of burning hydrogen.	(c) Catalyst
4. A gas formed when hydrogen reacts with chlorine in diffused sunlight.	(d) Reduction reaction
5. Converting liquid vegetable oils into solid ghee with the help of hydrogen.	(e) Pale blue

Answer :

Column A	Column B
1. A substance which speeds up the rate of chemical reaction.	(a) Catalyst
2. A reaction in which hydrogen removes oxygen from heated metal oxides.	(b) Reduction reaction
3. The colour of flame of burning hydrogen.	(c) Pale blue
4. A gas formed when hydrogen reacts with chlorine in diffused sunlight.	(d) Hydrochloric acid gas
5. Converting liquid vegetable oils into solid ghee with the help of hydrogen.	(e) Hydrogenation

Que: D. Write ‘True’ or ‘False’ for the following statements :

Statements	True/False
1. Hydrogen gas is used in filling weather observation balloons.	T
2. A mixture of hydrogen and chlorine reacts silently with each other in direct sunlight.	F
3. Oxyhydrogen flame has a temperature of 2800°C.	T
4. Hydrogen reacts with lead oxide to form lead metal and oxygen.	T
5. Hydrogen gas burns in air with a pale green flame.	F

Que: E. Tick (√) the most appropriate answer :

1. Hydrogen gas burns in air with a :

(a) pale yellow flame

(b) pale pink flame

(c) pale blue flame

(d) pale green flame

Answer: option (c) pale blue flame is correct.

2. The colour of residue left behind when hydrogen gas is passed over heated copper oxide is :

(a) black

(b) reddish

(c) brownish

(d) silvery white

Answer: option (b) reddish is correct.

3. Hydrogen reduces ………….. to metals on heating

(a) metal oxides

(b) metal sulphates

(c) metal sulphides

(d) metal chlorides

Answer: option (a) metal oxides is correct.

4. The process of removing oxygen from the metallic compounds containing oxygen is called :

(a) oxidation

(b) reduction

(c) displacement

(d) synthesis

Answer: option (b) reduction is correct.

5. Hydrogen reacts with lead oxide (heated) to form :

(a) Lead hydride and water

(b) Lead and water

(c) Lead hydroxide and water

(d) Lead hydroxide only

Answer: option (a) Lead hydride and water is correct.

STUDY QUESTIONS

Properties Uses of Hydrogen Class-8th Goyal Brothers ICSE Chemistry Solutions Ch-7 Unit-2

Question: 1. State five physical properties of hydrogen gas.

Answer: Physical properties of hydrogen –

1. Hydrogen is colourless, odourless and tasteless gas.
2. It is insoluble in water.
3. Vapour density of hydrogen is 1.
4. It is difficult to liquefy it as it liquefies at 243°C at a pressure of 20 atm.
5. It is combustible diatomic gas.

Question: 2. Describe your observations when :

(a) a mixture of hydrogen and sir is exposed to candle flame.

Answer: when a mixture of hydrogen and air us exposed to candle flame the gas burns with a pop with a ogle yellow flame.

(b) hydrogen burns in air.

Answer: when hydrogen burns in air it reacts with atmospheric oxygen to form water molecules.

Question: 3. State your observations when equal volumes of hydrogen and chlorine are exposed to :

(a) diffused sunlight

Answer: Diffused light is a soft, diffused light that lacks the brightness and intensity of direct light. It diffuses and spreads out in all directions. As a result, it appears to encircle objects. It is a softer light that doesn’t cast harsh shadows.

(b) direct sunlight

Answer: When the Sun is high in the sky and directly casting its rays on the surface, especially in the summer months, this is direct sunlight.

Question: 4. Briefly describe your observations when hydrogen gas is passed over heated copper oxide.

Answer: When hydrogen gas is passed over hot copper oxide, the black coating on the surface turns brown as the reverse reaction takes place and copper is obtained.

Question: 5. State four uses of hydrogen gas.

Answer: State four uses of hydrogen gas:

• Hydrogen has many actual and potential uses.
• Hydrogen is used in industrial processes.
• Hydrogen fuel cells produce electricity.
• Hydrogen can be burned for electricity generation and heating.

Question: 6. State two tests of hydrogen gas.

Answer: State two tests of hydrogen gas:

Question: 7. Why is the mixture of hydrogen and helium used in weather observation balloons, instead of pure hydrogen?

Answer: Hydrogen gas is replaced by helium itself or by a mixture of helium and hydrogen because if we use only hydrogen then by chance if there is any leakage in the balloon then it might cause the release of hydrogen gas in the air and this will cause an explosion. Because of this reason we use a mixture of gases.

Question: 8. By giving examples explain the following terms :

(a) Oxidation

Answer: The term oxidation was used to describe reactions where an element combines with oxygen. For example, the oxidation of magnesium involves the chemical reaction between magnesium metal and oxygen to form magnesium oxide.

(b) Reduction

Answer: Reduction is the chemical process in which a species gains electrons or loses oxygen. This is mainly used for extracting irons from ores. Reduction is observed in our day-to-day activity, and respiration is one example.

— : end of Properties Uses of Hydrogen Class-8th Goyal Brothers ICSE Chemistry Solutions Ch-7 Unit-2 :–

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