CG Board Class 8 Science Chapter 6 Solutions: Carbon (कार्बन) – 2026-27

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CG SCERT (Chhattisgarh Board) Class 8 Science & Technology Solutions | 2026-27 Official Edition

Welcome to the complete, 100% textbook-grounded CG Board Class 8 Science Chapter 6 Solutions: Carbon (कार्बन) in Bilingual Format (English Medium + हिंदी माध्यम). Every in-text question (Answer these / इनके उत्तर दीजिए) and end-of-chapter exercise (Exercises / अभ्यास के प्रश्न) has been solved strictly from the official 2026-27 SCERT Chhattisgarh Raipur textbook.

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Question 1

In which forms do we find carbon in…


📝 Question:

In which forms do we find carbon in our surroundings? – ?

💡 Solution:

Carbon is found in both free and combined states in our surroundings

  1. Free State: Found as allotropes such as diamond, graphite, coal, lamp black (kajal), wood charcoal, and fullerene.
  2. Combined State:
  • As calcium carbonate in limestone, chalk, and marble.
  • As carbon dioxide gas in air.
  • In food nutrients such as carbohydrates, fats, proteins, and vitamins.
  • In hydrocarbons such as natural gas, cooking gas (LPG), petrol, diesel, kerosene, and paraffin wax.

Question 2

What is allotropy


📝 Question:

What is allotropy? ?

💡 Solution:

Different physical forms of an element having different physical properties but identical chemical properties are called allotropes. The phenomenon of an element existing in different physical forms is called allotropy.

Question 3

Write two uses of diamond


📝 Question:

Write two uses of diamond

💡 Solution:

  1. Gemstone in Ornaments: Due to its exceptional brilliance and sparkle, diamond is used as a precious stone in jewelry.
  2. Cutting and Drilling Tool: Being the hardest natural substance, diamond is used for cutting glass and in drilling hard rocks.

Question 4

Write the methods of preparation of a Wood…


📝 Question:

Write the methods of preparation of: (a) Wood charcoal (b) Lamp black (Kajal)

💡 Solution:

(a) Wood Charcoal:** Prepared by heating wood shavings or wood pieces in a closed container (or boiling tube closed with a cork) in a limited supply of air (destructive distillation).

  • (b) Lamp Black (Kajal): Prepared by burning mustard oil or kerosene in an earthen lamp with a wick and collecting the black soot/layer deposited on an inverted glass slide or plate held over the flame.

Question 1

What is the name of the compound which…


📝 Question:

What is the name of the compound which is made of hydrogen and carbon? ?

💡 Solution:

The compound made of carbon and hydrogen in various proportions is called a hydrocarbon. (Examples: Methane, Ethane, Propane).

Question 2

What is combustion


📝 Question:

What is combustion? ?

💡 Solution:

The chemical process in which a combustible substance reacts with oxygen in the air upon heating to evolve heat and light (or both energy forms) is called combustion. Combustion is an oxidation reaction.

Question 3

Write names of three combustible substances


📝 Question:

Write names of three combustible substances

💡 Solution:

Three combustible substances are

  1. Magnesium ribbon
  2. Coal
  3. Wood / Paper

Question 4

Why are crackers and fuels not allowed to…


📝 Question:

Why are crackers and fuels not allowed to be carried in public vehicles? ?

💡 Solution:

Crackers and liquid fuels have very low ignition temperatures and high volatility. They catch fire easily upon minor friction, heat, or sparks, generating dangerous fire, gas, and explosions. Carrying them in crowded public vehicles poses a extreme risk of severe fire accidents, threatening lives and public property.

Question 1

What are the favourable conditions for combustion


📝 Question:

What are the favourable conditions for combustion? – ?

💡 Solution:

The three essential conditions required for combustion are

  1. Presence of a combustible substance (e.g., fuel, wood, coal).
  2. Continuous supply of air / oxygen (supporter of combustion).
  3. Heating the substance to attain its ignition temperature.

Question 2

What is ignition temperature


📝 Question:

What is ignition temperature? ?

💡 Solution:

The minimum temperature at which a combustible substance catches fire and starts burning in the presence of air is known as its ignition temperature.

Question 3

From which substance do we get a flame


📝 Question:

From which substance do we get a flame? ?

💡 Solution:

A flame is produced only by combustible substances that turn into gaseous vapors upon heating (e.g., wax vapors, camphor, LPG).

Question 4

Which is the hottest zone of the flame


📝 Question:

Which is the hottest zone of the flame? ?

💡 Solution:

The outermost zone (light-bluish non-luminous zone) of the flame is the hottest zone because complete combustion of unburnt fuel occurs here due to abundance of oxygen.

Question 5

Draw a well labelled diagram of candle to…


📝 Question:

Draw a well labelled diagram of candle to depict various zones of flame

💡 Solution:

Below is the labeled structure and breakdown of the three candle flame zones

`text

/ <- Outermost Light Blue Zone (Hottest zone, Complete combustion)

/ <- Middle Bright Yellow Zone (Moderate heat, Partial combustion)

/ || <- Innermost Dark Zone (Least hot, Unburnt wax vapors)

| || | <- Wick

|____| <- Candle Body

  • Outermost Zone (Light Blue): Non-luminous, complete combustion, highest temperature.
  • Middle Zone (Bright Yellow): Luminous, partial/incomplete combustion, moderate temperature.
  • Innermost Zone (Dark Black): Around the wick, unburnt wax vapors, lowest temperature.

Question 1

Why does limewater turn milky on passing carbon…


📝 Question:

Why does limewater turn milky on passing carbon dioxide through it? ?

💡 Solution:

When carbon dioxide (CO2) gas is passed into fresh lime water [calcium hydroxide, Ca(OH)2], it reacts chemically to form insoluble calcium carbonate (CaCO3) precipitate, which turns the solution milky white.

Ca(OH)2 (aq) + CO2 (g) → CaCO3 (s) ↓ + H_2O (l)

Lime water + Carbon dioxide → Calcium carbonate (Insoluble, Milky) + Water

Question 2

What is dry ice What is its use


📝 Question:

What is dry ice? What is its use? ? ?

💡 Solution:

Solidified carbon dioxide formed by cooling and compressing CO2 gas is known as dry ice.

  • Use: It is used as a coolant (refrigerant) for preserving perishable food, ice creams, and medical items at very low temperatures.

Question 3

Which gas is produced after chemical reaction in…


📝 Question:

Which gas is produced after chemical reaction in a fire extinguisher? Why is this gas used to extinguish fire? ? ?

💡 Solution:

Gas Produced: Carbon dioxide (CO2)** gas.

  • Reason for Use: Carbon dioxide gas does not burn itself and does not support combustion. Being heavier than air, it forms a blanket over the burning material, cutting off the supply of oxygen and extinguishing the fire safely.

Q17

Graphite is not used a As lubricant b…


📝 Question:

Graphite is not used:* (a) As lubricant (b) In electrodes (c) In pencil lead (d) In cutting instrument

💡 Solution:

(d) In cutting instrument**

Q18

Carbon dioxide converts blue litmus into red thus…


📝 Question:

Carbon dioxide converts blue litmus into red, thus it is an:* (a) Acidic oxide (b) Alkaline/basic oxide (c) Neutral oxide (d) None of these

💡 Solution:

(a) Acidic oxide**

Q19

Carbon allotrope with 60 atoms is a Fullerene…


📝 Question:

Carbon allotrope with 60 atoms is:* (a) Fullerene (b) Graphite (c) Diamond (d) Charcoal

💡 Solution:

(a) Fullerene**

Q20

Dry ice is a Solid CO2 b Liquid…


📝 Question:

Dry ice is:* (a) Solid CO2 (b) Liquid CO2 (c) Gaseous CO2 (d) Solid CO

💡 Solution:

(a) Solid CO2**

Q21

The hardest substance in nature is a Graphite…


📝 Question:

The hardest substance in nature is:* (a) Graphite (b) Stone (c) Diamond (d) Charcoal

💡 Solution:

(c) Diamond**

Q22

Which zone of the flame has the highest…


📝 Question:

Which zone of the flame has the highest temperature?* (a) Inner dark zone (b) Shining and bright middle zone (c) Light blue zone (d) Unlighted zone

💡 Solution:

(c) Light blue zone**

Q23

Allotropy is a characteristic of a Element b…


📝 Question:

Allotropy is a characteristic of:* (a) Element (b) Compound (c) Mixture (d) All of these

💡 Solution:

(a) Element**

  1. Combination of combustible gaseous substances produces flame.
  2. Because of its softness graphite is used in pencil lead.
  3. Diamond is the hardest allotropic form of carbon.
  4. Carbon dioxide is a colourless, odourless gas.
Q1

Statement Both graphite and diamond have the same…


📝 Question:

Statement: Both graphite and diamond have the same element, carbon in it. * Status: Correct

💡 Solution:

Q2

Statement Diamond is a good conductor of electricity


📝 Question:

Statement:** Diamond is a good conductor of electricity.

💡 Solution:

  • Status: Wrong
  • Correct Statement (English): Diamond is a bad conductor of electricity (Graphite is a good conductor).

Q3

Statement The light blue zone in flame is…


📝 Question:

Statement:** The light blue zone in flame is in the middle of the flame.

💡 Solution:

  • Status: Wrong
  • Correct Statement (English): The light blue zone is the outermost zone of the flame.

Q4

Statement Combustion doesnt take place in the outer…


📝 Question:

Statement:** Combustion doesn’t take place in the outer zone of the flame.

💡 Solution:

  • Status: Wrong
  • Correct Statement (English): Complete combustion takes place in the outer zone of the flame.

Q5

Statement Carbon dioxide is of alkaline nature Status…


📝 Question:

Statement: Carbon dioxide is of alkaline nature. Status: Wrong Correct Statement (English): Carbon dioxide is of acidic nature. : Exercise 4: Match the columns | Column A | Column B | Matching Option | | :— | :— | :— | | 1. Lamp black and charcoal | Solid carbon dioxide | Carbon allotrope | | 2. Made of 60 carbon atoms | Oxidation | Fullerene | | 3. Hardest substance | Carbon allotrope | Diamond | | 4. Dry ice | Fullerene | Solid carbon dioxide | | 5. Combustion | Diamond | Oxidation | Exercise 5: Answer the following questions Question 1: What do you understand by allotropy? What are the different allotropes of carbon? Write two uses of each. * ? – ? –

💡 Solution:

Allotropy:** The phenomenon in which an element exists in different physical forms with distinct physical properties but identical chemical properties is called allotropy.

  • Allotropes of Carbon and Two Uses Each:
  1. Diamond: Used in ornaments as a precious gem; used for glass cutting and rock drilling.
  2. Graphite: Used for making pencil leads; used as electrodes in battery cells and in crucibles.
  3. Wood Charcoal: Used as an absorbent of toxic gases due to its porous nature; used to decolorize sugar solution.
  4. Lamp Black (Kajal): Used in making black printing inks/paints; used as a supplement in vehicle tyres.
  5. Fullerene: Used in manufacturing semiconductors and superconductors; C-60 is researched for AIDS prevention/treatment.

Question 2

How will you differentiate between graphite and diamond


📝 Question:

How will you differentiate between graphite and diamond? ?

💡 Solution:

PropertyDiamondGraphite
HardnessHardest natural substanceSoft, smooth, and slippery
Electrical ConductivityBad conductor of electricityGood conductor of electricity
Thermal ConductivityVery good conductor of heatNormal conductor of heat
Primary UsesCutting glass, gemstones in jewelryPencil leads, battery electrodes, lubricants

Question 3

What is Fullerene What are its main uses


📝 Question:

What is Fullerene? What are its main uses? ? ?

💡 Solution:

Fullerene:** Discovered in 1985 by heating graphite to a high temperature, Fullerene is a spherical allotrope of carbon where 60 or more carbon atoms (C-60, C-70, C-90) bond together in a hollow cage-like spherical molecule. It was named after American architect Buckminster Fuller.

  • Main Uses:
  1. Used in manufacturing superconductors, semiconductors, lubricants, catalysts, and electric wires.
  2. C-60 substances are being utilized in research for preventing and curing AIDS.

Question 4

Draw a labelled diagram showing the preparation of…


📝 Question:

Draw a labelled diagram showing the preparation of carbon dioxide

💡 Solution:

Preparation Principle:** Carbon dioxide (CO2) is prepared in the laboratory by reacting sodium carbonate (washing soda, Na_2CO3) with lemon juice (citric acid) or dilute acid.

Washing Soda + Lemon Juice (Acid) → Carbon Dioxide + Salt + Water

Na_2CO3 (s) + 2HCl (aq) → 2NaCl (aq) + H_2O (l) + CO2 (g) ↑

  • Reaction with Base (Sodium Hydroxide):

CO2 (g) + 2NaOH (aq) → Na_2CO3 (aq) + H_2O (l)

  • Diagram Structural Setup:
  • Apparatus: Stand, test tube fitted with a single-hole cork, delivery tube, and gas collecting tube.
  • Reagents: Washing soda at the bottom of the test tube, lemon juice poured from top.
  • Gas Evolved: Carbon dioxide (CO2) collected in the jar.

Question 5

What is dry ice What are its important…


📝 Question:

What is dry ice? What are its important uses? ? ?

💡 Solution:

Dry Ice:** Solid carbon dioxide (CO2) formed by cooling and compressing carbon dioxide gas is called dry ice.

  • Important Uses:
  1. Used as a coolant/refrigerant in cold storage.
  2. Used to preserve frozen foods, milk products, and medicines during transportation.

Question 6

What are the main parts of candle flame…


📝 Question:

What are the main parts of candle flame? Explain with a diagram. – ?

💡 Solution:

A candle flame has three distinct zones

  1. Innermost Dark Zone: Area around the wick consisting of unburnt wax vapors. It lacks oxygen, hence no combustion occurs. Temperature is lowest.
  2. Middle Luminous Zone: Yellow and bright zone where wax vapors burn partially due to limited oxygen supply. It produces moderate heat and leaves soot.
  3. Outermost Non-Luminous Zone: Light blue zone where unburnt vapors burn completely due to abundant oxygen supply. It has the highest temperature.

Question 7

Give reasons a Diamond is used in ornaments…


📝 Question:

Give reasons: (a) Diamond is used in ornaments. (b) Diamond is used in cutting instruments. (c) Graphite is used as lubricant. (d) Graphite is used in electrodes. (e) Petrol is not used in cooking stoves

💡 Solution:

(a)** Diamond has exceptional luster. When properly cut, light rays undergo multiple internal reflections inside it before emerging, causing it to sparkle brilliantly.

  • (b) Diamond is the hardest known natural substance, enabling it to cut and drill through hard materials like glass and rocks.
  • (c) Graphite has a slippery, smooth, layered crystal structure where layers slide over each other easily, making it an excellent dry lubricant.
  • (d) Graphite contains free electrons in its crystal structure, making it a good conductor of electricity with a very high melting point.
  • (e) Petrol has a very low ignition temperature and vaporizes rapidly. In a stove, it catches fire explosively and uncontrollably.

Question 8

The colour of flame in Fatimas gas stove…


📝 Question:

The colour of flame in Fatima’s gas stove is blue and Rajesh’s is yellow. Who will cook faster and why? ?

💡 Solution:

Fatima will cook faster**.

  • Reason: A blue flame signifies complete combustion of fuel in the presence of sufficient oxygen, generating maximum heat energy (highest temperature zone). A yellow flame indicates incomplete combustion due to insufficient oxygen, generating less heat and wasting fuel as soot.

Question 9

Why doesnt charcoal burn with flames


📝 Question:

Why doesn’t charcoal burn with flames? ?

💡 Solution:

A flame is produced only when a combustible solid or liquid vaporizes into gas upon heating. Charcoal is a non-volatile solid carbon form that does not vaporize; hence, it glows red without producing a flame.

Question 10

Can blue flame be formed inside in the…


📝 Question:

Can blue flame be formed inside in the candle? Justify. ?

💡 Solution:

Answer:** No, a blue flame cannot form in the innermost region of a candle flame.

  • Justification: A blue flame requires complete combustion, which occurs only when plenty of fresh air/oxygen is available. In the innermost zone around the wick, oxygen cannot reach, so unburnt wax vapors accumulate without undergoing combustion, creating a dark zone.

Question 1

What happens to the candles


📝 Question:

What happens to the candles? ?

💡 Solution:

Both candles get extinguished one after the other.

Question 2

Why does it happen


📝 Question:

Why does it happen? ?

💡 Solution:

The chemical reaction between baking soda (sodium hydrogen carbonate) and vinegar (acetic acid) produces carbon dioxide (CO2) gas. CO2 gas is heavier than air, so it collects at the bottom of the bowl, displacing oxygen and extinguishing the candle flames.

Question 3

In what order does it happen


📝 Question:

In what order does it happen? ?

💡 Solution:

First the shorter candle gets extinguished, followed by the taller candle. This occurs because dense carbon dioxide gas fills the bowl starting from the bottom up.

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