Non Metals Class 9 Extra Questions and Answers Kerala Syllabus Chemistry Chapter 7

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Kerala Syllabus Std 9 Chemistry Chapter 7 Non Metals Extra Questions and Answers

Question 1.
a) What are the chemicals required for the laboratory preparation of Hydrogen?
b) Hydrogen-filled balloons rise up in the air. Why?
Answer:
a) Zinc and Hydrochloric acid
b) The density of hydrogen is less than air.

Question 2.
Hydrogen is used as a fuel because of its high calorific value.
a) What is calorific value?
b) Write any other advantage of hydrogen fuel.
c) Hydrogen is not commonly used as domestic fuel. Give reason
Answer:
a) The calorific value of a fuel is the heat energy released from one unit mass of that fuel on complete combustion.
b) Availability is plenty / High calorific value/pollution free.
c) Bum with an explosion, it is very difficult to store and transport.

Question 3.
a) What are the chemicals required to prepare hydrogen in the laboratory?
b) Write the balanced chemical equation of this reaction?
c) Which type of reaction is this?
Answer:
a) Dilute hydrochloric acid and Zinc
b) Zn + 2HCl → ZnCl₂ + H₂
c) Displacement reaction

Question 4.
List the uses of hydrogen
Answer:

• For the industrial production of ammonia and methanol.
• To saturate unsaturated oils.
• As a fuel.

Question 5.
a) Which fuel has the highest calorific value?
b) What will be the product formed when hydrogen burns in the air?
Answer:
a) Hydrogen
b) Water (H₂O)

Question 6.
Write the reaction between Hydrogen and chlorine.
Answer:
Hydrogen combines with chlorine in the presence of sunlight to form hydrogen chloride.
H₂2 + Cl₂ 2HCl

Question 7.
Write any three properties of Hydrogen.
Answer:
Insoluble in water, Hydrogen gas bums with a pop sound, Hydrogen is a colourless and odourless gas

Question 8.
Carbon is an element that shows allotropy.
a) What is allotropy?
b) Non-crystalline allotropes of carbon are commonly called __________
Answer:
a) Different forms of the same element having different physical properties but with the same chemical properties are known as Allotropes, and this phenomenon is called Allotropy.

b) Amorphous carbon.
The structure of two crystalline allotropes of carbon is given below,

Question 9.
The structure of two crystalline allotropes of carbon is given below.
a) Which among these is the structure of a diamond?


b) Which of these crystalline structures has no free electron?
c) Graphite is used as a lubricant. Why?
Answer:
a) Figure B
b) Figure B (Diamond)
c) Layers are held together by weak van der Waals forces. Hence, one layer can slide over another.

Question 10.
Carbon monoxide and carbon dioxide are two compounds formed by the combination of carbon and oxygen.
a) Write the balanced chemical equation showing the formation of carbon monoxide
b) Which are the gases mixed with carbon monoxide to prepare water gas and producer gas respectively?
c) Inhaling of excess carbon monoxide leads even to death. Why?
Answer:
a) 2C + O₂→ 2CO
b) Water gas → CO + H₂, Producer gas → CO + N₂
c) It reacts with the haemoglobin in the blood and forms carboxyhaemoglobin. As a result, the oxygen-carrying capacity of blood decreases, leading even to death.

Question 11.
When eggshell is added to Hydrochloric acid, a gas is produced.
a) Identify this gas.
b) Write the chemical equation of this reaction.
Answer:
a) Carbon dioxide
b) CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂

Question 12.
Carbon dioxide (CO₂) is an important oxide of carbon.
a) Name the process by which CO₂ is utilised by plants.
b) Write an environmental problem due to the tremendous increase in the amount of CO₂ in the atmosphere.
c) What is dry ice? Write any one use.
Answer:
a) Photosynthesis
b) Climate change/ Greenhouse effect
c) The solid form of carbon dioxide.
Used as refrigerant / To create foggy effects in stage shows.

Question 13.
Writ any three uses of carbon dioxide.
Answer:
As gaseous fuel, To produce industrial fuels like water gas and producer gas, As a reducing agent in metallurgy.

Question 14.
a) Why does graphite conduct electricity?
b) Write any two properties of graphene
c) What are Buckyballs and Buckytubes?
Answer:
a) Graphite conducts electricity due to delocalised electrons and layered structure.

b) High electrical conductivity
High thermal conductivity

c) Fullerene has a hollow spherical structure consisting of pentagons and hexagons. They are
known as Bucky balls.
Fullerene with a cylindrical structure is used as carbon nanotubes. These are called Buckytubes.

Question 15.
What are the different ways in which nitrogen is obtained by plants?
Answer:

• By decomposition
• Through fertilisers
• By nitrogen fixing by bacteria

Question 16.
“It is said that lightning is a boon to plants”. Justify the statement.
Answer:
During lightning, the triple bond in nitrogen breaks, and nitrogen combines with the atmospheric oxygen to form nitric oxide (NO)
N₂ + O₂ → NO
Nitric oxide thus combines with oxygen to form nitrogen dioxide (NO₂)
2NO + O₂ → 2NO₂
Nitrogen dioxide dissolves in rainwater in the presence of oxygen and reaches the soil as nitric acid (HNO₃)
4NO₂ + 2H₂O + O₂ → 4HNO₃
Nitric acid reacts with the minerals in the soil to form nitrate salts, which the plants absorb. So, it is said that lightning is a boon to plants.

Question 17.
Can you list out which other means are there for getting a greater amount of elements for plants?
Answer:

• Use of organic fertilisers
• Use chemical fertilisers
• Bio decomposition
• Through nitrogen fixation

Question 18.
Write any two advantages of using organic fertilizers.
Answer:
Eco-friendly, Preserve the nature of the soil.

Question 19.
Nitrogen is inert in nature. Because it contains ………………. in the molecule.
(a) single bond (b) double bond (c) triple bond (d) ionic bond
Answer:
Triple bond

Question 20.
Classify the following gases into molecules having single bond, double bond and triple bond (a) Nitrogen (b) Chlorine (c) oxygen
Answer:
Single bond – Chlorine, Double bond – Oxygen, Triple Bond – Nitrogen

Question 21.
List the merits and limitations of the application of organic fertilisers.
Answer:
Merits:

• Eco friendly
• Preserve the nature of the soil

Limitations:

• Biodegradation needs time, so it cannot easily be absorbed by plants in time.
• The presence of microorganisms is necessary.
• Storage and transportation are not easy

Question 22.
Heat potassium permanganate in a dry boiling tube. When a glowing match stick is shown into
this boiling point tube, it flares up.
a) The presence of which gas is indicated by the flaring up of the glowing match stick?
b) Write down the chemical equation of the reaction taking place in the boiling tube.
c) To which category does this reaction belong?
Answer:
a) Oxygen
b) 2KMnO₄ + Heat → K₂MnO₄ + MnO₂ + O₂
c) Decomposition

Question 23.
Suggest a method to prepare oxygen in the laboratory
Answer:
Oxygen can be produced in the laboratory by the strong heating of potassium permanganate. 2KMnO₄ + heat → K₂MnO₄ + MnO₂ + O₂
Oxygen can also be prepared in the laboratory, by adding a small pinch of manganese dioxide in hydrogen peroxide (H₂O₂)
2H₂O₂ → 2H₂O + O₂

Question 24.
a) What is ozone?
b) Where is ozone found in the atmosphere?
c) What are chlorofluorocarbons (CFCs)?
Answer:
a) Ozone is an allotrope of oxygen. Three oxygen atoms combine to form an ozone molecule, O3.
b) In the stratosphere.
c) Chlorofluorocarbons are a class of compounds containing chlorine fluorine and carbon.

Question 25.
How CFC causes ozone layer depletion.
Answer:
Chlorofluorocarbons released into the atmosphere reach the stratosphere and break down by the action of ultraviolet radiations and release chlorine. This chlorine decomposes ozone molecules into oxygen. This disturbs the equilibrium in the ozone-oxygen cycle process.

Question 26.
What is the importance of ozone in the atmosphere?
Answer:
Ozone acts like a shield, protecting us from the sun’s harmful rays. It forms and breaks down in a continuous cycle to maintain a balance.

• The sun emits harmful ultraviolet (UV) radiation.
• UV radiation breaks apart oxygen molecules (O₂) into oxygen atoms (O).
• These oxygen atoms combine with other oxygen molecules to form ozone (O₃)
• Ozone absorbs more harmful UV radiation, protecting Earth’s surface.
• Some ozone molecules break down back into oxygen, but the formation of new ozone balances this process.
• This constant cycle helps maintain a stable level of ozone in the atmosphere, protecting us from harmful UV rays.

Question 27.
What are the uses of oxygen?
Answer:

• It’s the breath of life for all living organisms.
• For combustion, oxygen is necessary.
• As an oxidant in rocket fuels.
• For artificial respiration.
• For decomposition of wastes.

Question 28.
How can we reduce the rate of depletion of the ozone layer?
Answer:
Today, the use of CFC is being controlled in most countries. Harmful CFCs are replaced nowadays with safer substances. This has helped in reducing the rate of depletion of the ozone layer.

Question 29.
The picture given below shows the laboratory preparation of chlorine. Analyse the picture and answer the following questions.

a) What are the chemicals required for the preparation of chlorine gas?
b) Why is chlorine gas passed through water?
c) Which substance is used to remove moisture from chlorine?
d) How is bleaching powder prepared?
Answer:
a) KMnO₄ & HCl
b) To remove the traces of hydrogen chloride vapours that come out along with chlorine.
c) Sulphuric acid (H₂SO₄)
d) By passing dry chlorine gas over dry slaked lime.

Question 30.
List out the chlorine compounds you are familiar with.
Answer:
Hydrogen chloride (HCl), Sodium chloride (NaCl), Potassium chloride (KCl)

Question 31.
In the laboratory preparation of chlorine, why is chlorine gas passed through water?
Answer:
Hydrogen chloride vapours coming along with chlorine is removed by passing it through water.

Question 32.
Write the balanced chemical equation for the preparation of chlorine. Write the name of the reactant involved in the preparation of chlorine.
Answer:
2KMnO₄ + 16HCl → 2KCl + 2MnCl₂ + 8H₂O + 5Cl₂
Potassium permanganate and Con. HCl are the reactants.

Question 33.
Write the uses of chlorine.
Answer:
For bleaching.
For the preparation of insecticides.
For removing stains in the fabrics.
For purification of water.
For the preparation of bleaching powder.

Question 34.
How is bleaching powder produced, and what is the chemical process involved in its bleaching action?
Answer:
Bleaching powder is prepared by passing dry chlorine gas over dry slaked lime. Chlorine gas reacts
with the water to give hydrochloric acid and hypochlorous acid (HClO).
Cl₂ + H₂O → HCl + HOCl
Hypochlorous acid decomposes and liberates atomic oxygen
HOCl → HCl + [O] This atomic oxygen oxidises coloured substances

Question 35.
Which of the following is used to purify water?
(a) Hydrogen
(b) Oxygen
(c) Nitrogen
(d) Chlorine
Answer:
(d) Chlorine

Question 36.
Chlorine gas is passed through concentrated sulphuric acid. Why?
Answer:
Sulphuric acid can absorb the water vapour present in chlorine gas when it passes through the concentrated sulphuric acid (as a drying agent).