Class-8 Dalal Simplified Carbon and Its Compound ICSE Chemistry

Class-8 Dalal Simplified Carbon and Its Compound ICSE Chemistry Dr Viraf J Dalal Middle School Allied Publishers Solutions. Chapter-9. We Provide Step by Step Solutions of Exercise/Lesson -9 Carbon & Its Compound with Objective Type Questions, Fill in the blanks and Give reason , Match the following of Dr Viraf J Dalal Middle School Chemistry Allied Publishers. Visit official Website CISCE for detail information about ICSE Board Class-8.

Carbon and Its Compound Class-8 Dalal ICSE New Simplified Chemistry Dr Viraf J Dalal Middle School Allied Publishers Solutions. Chapter-9


EXERCISE-9

Question 1.
Differentiate between the two branches of chemistry – organic chemistry & inorganic chemistry with suitable examples.
Answer 1:

Organic chemistry : “A branch of science that deals with the study of carbon compounds with hydrogen and oxygen.”
methane CH4,.

ethane C2H6,

Acetic acid CH3COOH,

methyl alcohol.CH4OH

Inorganic chemsitry : “A branch of science that deals with the study of compound other than Carbon  (Exception–oxides of carbon, carbonates, metallic carbides are in inorganic while Carbon is present

H20 , NaCl, KBr,  HCl , NH3
e.g. H2C03 – carbonic acid, C02, CaC03 calcium carbonate.

Question 2.
State how carbon occurs in the free state and in the combined state.
Answer 2:

 In free state – diamond, graphite, in impure form as coal.

In combined state : cellulose in wood and limestone CaC03. and C02 in atmosphere, hydro-carbon fuel as natural gas, petroleum,

Question 3.
Define the term ‘allotropy’. Give a reason why carbon exhibits allotropy.
Answer 3:
Allotropy : –Allotropy is occurrence of an element in two or more forms which have the same chemical properties but differ in physical properties.

Diamond , graphite,  buckminsterfullerene

Carbon has a difference in atomic arrangement in the crystal structure which results in allotropy.

Question 4.
Name two crystalline and four amorphous allotropes of carbon.
Answer 4:
 two crystalline allotropes of carbon

  1. diamond
  2. graphite.

 four amorphous allotropes of carbon

  1. coal,
  2. coke
  3. lampblack
  4. wood charcoal.

Question 5.
Compare the structure of the crystal of diamond & graphite with special reference to the reason for diamond being the hardest natural substance while graphite one of the softest. Compare the electrical & thermal conductivity of the two crystalline allotropes of carbon.
Answer 5:

Structure of crystal of diamond :

  • It is the hardest natural substance due to the strength and uniformity of carbon. It exhibits carbon covalent bond i.e. tetrahedron structure.
  • It is a bad conductor of electricity and heat both, because of no availability free electrons to move.

Structure of graphite :

  • It is soft and greasy, because of the parallel layers of atoms of carbon held together by weak forces and forming a hexagonal structure.
  • It is a good conductor of electricity and heat, because of the availability of free electrons.

Question 6.
With reference to the structure of the two crystalline allotropes of carbon, state why diamond is inert or unreactive while graphite is comparably more reactive.
Answer 6:

The structure of diamond is compact and hence it is unreactive.

Graphite has an open structure which makes it more prone to chemical attack.

Question 7.
State the reasons for

(a) Use of diamond – as an. item of jewellery,

(b) Use of graphite –

(i) as a lubricant for heated machine parts,

(ii) as a lining for crucibles used in manufacture of high grade steel,

(iii) as an electrode in electroplating.
Answer 7:
(a) Use of diamond –  Diamond is used in making jewellery because it has a sparkling surface due to high refractive index. It can be cut and polished.

(b)

(i) Lubricants other than graphite can catch fire, graphite makes the parallel layers slide over one and other. It is non-volatile and non-sticky, reducing the friction between rotating parts of the vehicle.

(ii) Graphite can tolerate high temperatures because it is a good conductor of heat.

(iii) Graphite is a good conductor of electricity and relatively inert and does not react with acids.

Question 8.

State in brief the transformation of vegetable matter to different types of coal varying in carbon content. State two uses each of

(a) coal
(b) coke
(c) lampblack or soot.

Answer 8:

Slow bacterial decomposition of vegetable matter under the influence of heat from earth, high soil pressure of earth above it and absence of oxygen over million years causes transformation of vegetable matter into different types of coal.

Coal is used to manufacture paints and perfumes and to make insecticides, pesticides.

Coke is used as fuel in stoves, furnaces and manufactures steel and iron.

Lampblack is used in making shoe polish, ceramics and cement.

  1. 60%C is peat
  2. 65%C is lignite
  3. 85%C is bituminous
  4. 90%C is anthracite

Question 9.
‘Wood charcoal – an amorphous allotrope of carbon reduces heated metallic oxides to metals’. Give a balanced equation to support the statement.
Answer 9:
Wood charcoal act as reducing agent Hence ZnO, Fe2O3 reduced to Zn and Fe
new-simplified-chemistry-class-8-icse-solutions-carbon-its-compounds - 6

Question 10.
Carbon dioxide occurs both in the free state and in the combined state.
State three methods how carbon dioxide is added to the atmosphere.
Answer 10:
three methods how carbon dioxide is added to the atmosphere

  1. by Burning of Fuel (carbon compounds)
  2. by Death and decay of living being.
  3. by Respiration in living being.

Question 11.
In the laboratory preparation of carbon dioxide by action of a dilute acid on a metallic carbonate give –

(a) A balanced equation for the preparation

(b) A reason for

(i) use of a washer bottle containing cone. H2SO4 in the preparation

(ii) Not collecting the prepared gas over water

(iii) Not using dilute sulphuric acid as a reactant in the preparation.
Answer 11:
new-simplified-chemistry-class-8-icse-solutions-carbon-its-compounds - 6.1

(b)

  1. Cone. H2SO4 absorbs moisture from the gas in the washer bottle.
  2.  The prepared gas is C02 which does not collect over water because it is soluble in water.
  3. Dilute sulphuric acid when used as a reactant with calcium carbonate forms a coating of insoluble calcium sulphate and the reaction stops after a while.
    new-simplified-chemistry-class-8-icse-solutions-carbon-its-compounds - 6.2

Question 12.
How would you prove experimentally that

(a) Carbon dioxide does not support combustion
(b) Is slightly acidic in nature.

Answer 12:
(a) Carbon dioxide does not support combustion.

Proving by Experiment that CO2 does not support combustion: Bringing a burning candle in the mouth of gas jar which is full of CO2 gas. The candle is extinguished. confirming that  CO2 is non-supporter of combustion.
new-simplified-chemistry-class-8-icse-solutions-carbon-its-compounds - 7

(b) Proving by Experiment that CO2 Is slightly acidic- Bringing  a moist blue; litmus paper in the mouth of gas jar which is full of CO2 gas. which turn blue colour of paper into red. This confirm that CO2 gas is acidic in nature.
new-simplified-chemistry-class-8-icse-solutions-carbon-its-compounds - 7.1

Question 13.
Starting from carbon dioxide how would you obtain

(a) A weak acid
(b) A fertilizer
(c) A highly poisonous gas
(d) Black particles of carbon.

[Give balanced equations for the same] Answer 13:

(a)  A weak acid : when CO2 is dissolved in water, carbonic acid is formed.
new-simplified-chemistry-class-8-icse-solutions-carbon-its-compounds - 8
(b) A fertilizer– CO2 reacts with ammonia gas to form urea (a nitrogenous fertilizers).
new-simplified-chemistry-class-8-icse-solutions-carbon-its-compounds - 8.1
(c)  A highly poisonous gas -CO2 is reduced to a highly poisonous gas CO by carbon (coke).
new-simplified-chemistry-class-8-icse-solutions-carbon-its-compounds - 8.2
(d) Black particles of carbon. : Burning magnesium burns in CO2 making use of oxygen of CO2 producing black carbon particles.
new-simplified-chemistry-class-8-icse-solutions-carbon-its-compounds - 8.3

Question 14.
State how you would convert carbon dioxide to a metallic carbonate using a basic oxide e.g. sodium oxide. [Give a balanced equation] Answer 14:
We can turn a basic oxide turns into a carbonate when carbon dioxide is added to it.
Na2O + CO2 → Na2CO3

Question 15.
‘When carbon dioxide is bubbled into lime water, the lime water turns milky and when bubbled in excess the milkiness disappears’. Give balanced equations to support the statement.
Answer 15:
new-simplified-chemistry-class-8-icse-solutions-carbon-its-compounds - 8.4

When carbon dioxide is bubbled in excess, the milkiness of lime water disappears due to formation of bicarbonate which is soluble in water.
new-simplified-chemistry-class-8-icse-solutions-carbon-its-compounds - 8.5

Question 16.
Explain the term ‘dry ice’. State its application. Give three reasons why carbon dioxide finds application in fire extinguishers.
Answer 16:

Dry ice : The Solid carbon dioxide is called dry ice.

Applications of Dry ice : It ice is used as refrigerant for preservation of foods as it freezes faster and lasts longer than normal ice.

Three reasons why carbon dioxide finds application in fire extinguishers

  1. Carbon dioxide covers the fire like a blanket and cuts the contact of fire to the oxygen present in the air.
  2. Carbon dioxide is a non-combustible gas and it’s heavier than air.
  3. Carbon dioxide helps to bring the amount of air supply and the ignition temperature.

Question 17.

Using a magnesium ribbon, how would you prove that a given gas jar contains carbon dioxide.
Answer 17:

prove that a given gas jar contains carbon dioxide.

magnesium ribbon is burnt in a jar of gas and black particles are seen on the wall of the jar. When magnesium is burnt in carbon dioxide, it leaves behind black particles of carbon by taking away the oxygen.

This confirm that the jar was filled with carbon dioxide.

new-simplified-chemistry-class-8-icse-solutions-carbon-its-compounds - 9
Question 18.

State the function of cone, sulphuric acid in the laboratory preparation of carbon monoxide from oxalic acid.
Answer 18:
Concentrated sulphuric acid removes molecules of water from formic acid. It acts as a dehydrating agent in formation of carbon monoxide.

Question 19.

Give reasons why carbon monoxide is considered a highly poisonous gas. State why it is dangerous.

  1. To sleep in a closed room with a fuel burning
  2. To be in the vicinity of smokers.

Answer 19:

Carbon monoxide is considered highly poisonous because it combines with haemoglobin in the blood of a human body. It ultimately decreases the oxygen carrying capacity of blood.

  1. It is dangerous to sleep in a closed room with a fuel burning because the closed room already limits the supply of oxygen and the fumes of burning fuel contain carbon monoxide which combines with haemoglobin and decreases the oxygen carrying capacity of blood.
  2. The smoke of burning tobacco contains carbon monoxide.

Question 20.
Convert carbon monoxide to carbon dioxide using two different methods.
Answer 20:
Two Methods for converting CO into CO2.

1.) Burning carbon monoxide –

new-simplified-chemistry-class-8-icse-solutions-carbon-its-compounds - 10

2. ) Reduction of any metal oxide:

ZnO + CO → Zn + CO2

Question 21.
State how carbon monoxide finds application in

  1. The metallurgy of iron
  2. Preparation of an alcohol.
[Give balanced equations for the same] Answer 21:

1.)   CO helps in extracting  metal from their oxide of ore and reduces into metal

new-simplified-chemistry-class-8-icse-solutions-carbon-its-compounds - 10.1

2.) Preparation of alcohol :
new-simplified-chemistry-class-8-icse-solutions-carbon-its-compounds - 10.2


OBJECTIVE TYPE QUESTIONS

Carbon and Its Compound Class-8 Dalal ICSE New Simplified Chemistry Dr Viraf J Dalal Middle School Allied Publishers Solutions. Chapter-9

Question-.1. 

Name the following :

  1. A crystalline allotrope of carbon built up from a hexagonal unit.
  1. An allotrope of carbon used for the manufacture of coke.
  1. An amorphous allotrope of carbon which floats on water.
  2. An acid formed when carbon dioxide is dissolved in water under pressure.
  1. The gaseous product obtained when carbon monoxide is passed over heated iron [II] oxide.

Answer-1

  1. Graphite
  2. Coal
  3. Wood charcoal
  4. Carbonic acid
  5. Carbon dioxide

Question-2.

 Select the correct answer from A, B, C, D and E for each statement given below :

A : Anthracite
B : Diamond
C : Carbogen
D : Urea
E: Lampblack

  1. An allotrope of carbon used as a tip for deep boring drills.
  2. The type of coal with the highest carbon content.
  3. An allotrope of carbon obtained by burning kerosene oil in a limited supply of air.
  4. A nitrogenous fertilizer obtained from carbon dioxide.
  5. A compound which finds use for a victim of carbon monoxide poisoning.

Answer-2

  1. B. Diamond
  2. A. Anthracite
  3. E. Lampblack
  4. D. Urea
  5. C. Carbogen

 

Question-.3. 

Give a balanced equation for the following conversions : [In one or two steps]

  1. Coke to water gas
  2. Calcium bicarbonate to calcium nitrate using a dilute acid.
  3. Lime water to calcium bicarbonate.
  4. Carbon dioxide to carbon
  5. A metallic oxide to calcium carbonate.

Answer-3

(1) Coke to water gas
new-simplified-chemistry-class-8-icse-solutions-carbon-its-compounds - 11

(2) Calcium bicarbonate to calcium nitrate using a dilute acid.
new-simplified-chemistry-class-8-icse-solutions-carbon-its-compounds - 11.1

(3) Lime water to calcium bicarbonate.
new-simplified-chemistry-class-8-icse-solutions-carbon-its-compounds - 12

(4) Carbon dioxide to carbon
CO2 to carbon
On burning magnesium in CO2
new-simplified-chemistry-class-8-icse-solutions-carbon-its-compounds - 12.1

(5) A metallic oxide to calcium carbonate
new-simplified-chemistry-class-8-icse-solutions-carbon-its-compounds - 12.2

Question-.4.

 Complete the statements by filling the blanks with the correct word from the bracket.

  1. The crystal of ______ [diamond/graphite] is opaque to light and is a good conductor of heat.
  2. A graphite-clay mixture baked at high temperature is used in making ______ [lubricants/refractory cruscibles]
  3. Adsorption capacity of wood charcoal is increased by passing ____ [carbon dioxide/steam] over wood charcoal, at high temperature.
  4. ______ [organic/inorganic] chemistry is the chemistry of carbon compounds mainly of ‘carbon’, ‘hydrogen’ & ‘oxygen’.
  5. Sodium oxide combines with carbon dioxide to give _____ [sodium carbonate/sodium bicarbonate]

Answer-4

  1. Graphite
  2. Refractory crucibles
  3. Steam
  4. Organic
  5. Sodium bicarbonate

Question-.5. 

Give reasons for the following :

  1. Diamond & graphite are allotropic modifications of carbon.
  2. It is dangerous to stand behind a running engine of a vehicle.
  3. Both CO2 & SO2  turn lime water milky. Moist potassium permanganate paper helps in distinguishing the two gases.
  4. Carbon monoxide and not carbon dioxide is highly poisonous gas.
  5. Lime water finds application for testing both carbon dioxide & carbon monoxide gas individually.

Answer-5

(1) Diamond & graphite are allotropic modifications of carbon.

Diamond & graphite are carbon elements, their chemical properties are same i.e. they form CO2  on burning but differ in physical state. Hence they are allotropic modifications.

(2.) It is dangerous to stand behind a running engine of a vehicle.

A running engine produces carbon monoxide in the form of smoke it releases, which is dangerous for humans.

(3) Both SO2 and  CO2. turn lime water milky. Moist potassium permanganate paper helps in distinguishing the two gases.

SO2 turns the moist purple potassium permanganate paper to colourless, while CO2 gas has no effect on the moist purple permanganate.

(4) Carbon monoxide and not carbon dioxide is highly poisonous gas.

Carbon monoxide is considered highly poisonous because it combines with haemoglobin in the blood of a human body. It ultimately decreases the oxygen carrying capacity of blood.

(5) Lime water finds application for testing both carbon dioxide & carbon monoxide gas individually.

Carbon monoxide and carbon dioxide are passed through lime water. Carbon monoxide does not turn the lime water milky, while carbon dioxide turns limewater milky.

.– : End of Carbon & Its Compound Class-8 Dalal Solutions :–


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