9th Standard Science Carbon and its Compounds Solution in English

Lesson 15 Carbon and its Compounds

9th Science Guide: In this post, we will explore the topic of carbon and its compounds. Carbon is a versatile element that forms the basis of numerous organic compounds. We will delve into various aspects of carbon and its compounds through a series of questions and answers.

Carbon and its Compounds Book Back Answer

This Carbon and its Compounds Book Back Answers have four sections. “Choose the Correct Answer” is a multiple-choice section, “Fill in the Blanks” tests your recall and application of key concepts, “Match the following” challenges your knowledge of related concepts, and “Answer in Brief” requires concise explanations. Let’s explore carbon chemistry and assess your understanding. Let’s begin!

I. Choose the Correct Answer

1. A phenomenon in which an element exists in different modification in the same physical state is called

  1. Isomerism
  2. Allotropy
  3. Catenation
  4. Crystallinity

Ans: Allotropy

2. Carbon forms large number of organic compounds due to

  1. Allotropy
  2. Isomerism
  3. Tetravalency
  4. Catenation

Ans: Catenation

3. Nandhini brings his lunch every day to school in a plastic container that has resin code number 5. The container is made of

  1. Polystyrene
  2. PVC
  3. Polypropylene
  4. LDPE

Ans: Polypropylene

4. Plastics made of Polycarbonate (PC) and Acrylonitrile Butadiene Styrene (ABS) are made of resin code _______

  1. 2
  2. 5
  3. 6
  4. 7

Ans: 7

5. Graphene is one atom-thick layer of carbon obtained from

  1. Diamond
  2. Fullerene
  3. Graphite
  4. Gas Carbon

Ans: Graphite

6. The legal measures to prevent plastic pollution come under the ______ Protection Act 1988.

  1. Forest
  2. Wildlife
  3. Environment
  4. Human Rights

Ans: Environment

7. Number of free electron(s) in each carbon of graphite is

  1. one
  2. Two
  3. Three
  4. Four

Ans: one

8. The carbon atoms in fullerene are arranged in mixed

  1. Tetragon and Pentagon
  2. Pentagon and Hexagon
  3. Hexagon and Heptagon
  4. Heptagon and Octagon

Ans: Pentagon and Hexagon

9. Diamond is not a good conductor of electricity because

  1. it is very hard
  2. it has no free electron
  3. its structure is uniform
  4. it is insoluble in water

Ans: it has no free electron

10. Which of the following does not contain a double bond

  1. CO2
  2. C2H4
  3. HCl
  4. O2

Ans: HCl

11. Which of the following is highly toxic?

  1. Carbon dioxide
  2. Carbon monoxide
  3. Calcium carbonate
  4. Sodium bicarbonate

Ans: Carbon monoxide

12. Raagav brings his lunch every day to school in a plastic container which has resin code number 5. The container is made of

  1. Polystyrene
  2. PVC
  3. Polypropylene
  4. LDPE

Ans: Polypropylene

13. Which of the following plastic items are banned by the Government of Tamil Nadu as of 1st January 2019?

  1. Plastic sheets
  2. Plastic tea cups
  3. Plastic water packets
  4. All the above

Ans: All the above

14. Graphite is used as lubricant in machines because

  1. it is good conductor of electricity
  2. it is made of slippery layers and has high melting point
  3. it has high density
  4. it is strong and soft

Ans: it is made of slippery layers and has high melting point

15. The lead pencil contains

  1. Graphite
  2. Diamond
  3. Lead
  4. Charcoal

Ans: Graphite

16. Plastic resin codes are shown as three chasing arrows in a ____________ with a number in the middle or letters (an acronym of that plastic type).

  1. Logo
  2. Recycling symbol
  3. Square
  4. Triangle

Ans: Triangle

II. Fill in the Blanks

1. _________ named carbon.

Ans: Antoine Lavoisier

2. Buckminster Fullerene contains ______ carbon atoms.

Ans: 60

3. Compounds with the same molecular formula and different structural formula are knows as __________

Ans: Isomers

4. _________ is a suitable solven for sulphur

Ans: Allotropy

5. There are ________ plastic resin codes.

Ans: 7

6. Different methods of formation of carbon is the main reason for its __________

Ans: allotropes

III. Match the following

1. AlkyneBucky Ball
2. Andre GeimOxidation
3. C60Graphene
4. ThermocolTriple bond
5. BurningPolystyrene
Ans : 1 – D, 2 – C, 3 – A, 4 – E, 5 – B

IV. Answer in brief.

1. Differentiate graphite and diamond

1. Each carbon has four covalent bonds.Each carbon has three covalent bonds.
2. Hard, heavy, and transparent.Soft, slippery to touch and opaque.
3. It has tetrahedral units linked in three dimension.It has planar layers of hexagon units.
4. It is non-conductor of heat and electricity.It is conductor of heat and electricity.

2. Write all possible isomers of C4H10

9th Science Guide Carbon and its Compounds Answers in English a

3. Carbon do not form ionic compounds. Why?

It has four electrons in its outermost orbit. According to Octet Rule, carbon requires four electrons to attain nearest noble gas (Neon) electronic confi guration. So carbon has the tendency to share its four electrons with other atoms to complete its octet. So carbon do not form ionic compounds.

4. Define Allotrophy.

Allotropy is the property that an element can exist in more than one physically different and chemically identical form.

5. Why are one-time use and throwaway plastics harmful?

Use and throwaway plastics cause short and long-term environmental damage. Half of all the plastic made today is used for throwaway plastic items. These block drains and pollute water bodies. One-time use plastic causes health problems for humans, plants and animals.

6. What are saturated and unsaturated compounds called?

Organic compounds containing carbon. Carbon single bonds are known as saturated compounds. Organic compounds containing one (or) more double (or) triple bonds are known as unsaturated compounds

7. What is the valency of carbon in carbon monoxide?

The valency of carbon in carbon monoxide is two.

V. Answer in detail.

1. What is catenation? How does carbon form catenated compounds?

Catenation is the binding of an element to itself or with other elements through covalent bonds to form open-chain or closed-chain compounds. Carbon is the most common element which undergoes catenation and forms long-chain compounds. Carbon atom links repeatedly to themselves through a covalent bond to form a linear chain, branched chain, or ring structure.

This property of carbon itself is the reason for the presence of a large number of organic carbon compounds. So organic chemistry essentially deals with catenated carbon compounds.

2. What are the chemical reactions of carbon?

Oxidation – (Reaction with oxygen)

Carbon combines with oxygen to form its oxides like carbon monoxide (CO) and carbon dioxide (CO2) with evolution of heat.

2C(s) + O2(g)) → 2 CO(g)+ heat

C(s) + O2(g)→ C O2(g)+ heat

Reaction with steam

Carbon reacts with steam to form carbon monoxide and hydrogen. This mixture is called water gas.

C(s) + H2O(g) → C O(g) + H2(g)

Reaction with sulphur

With sulphur, carbon forms its disulphide at high temperature.

C(g) + S(g) → C S2(g)

Reaction with metals

At elevated temperatures, carbon reacts with some metals like iron, tungsten, Titanium, etc. to form their carbides.

W(s) + C(g) → WC(s)

3. Name the three safer resin codes of plastics and describe their features.

VI. Higher Order Thinking Skills

1. Why do carbon exist mostly in combined state?

Carbon exist mostly in combined state because of catenation,Tetra valency and formation of multiple bonds

2. When a carbon fuel burns in less aerated room, it is dangerous to stay there. Why?

When a carbon fuel burns in less aerated room, it produces carbon monoxide, which is highly toxic because it affects the oxygen carrying capacity of haemoglobin.so it is dangerous to stay there

3. Explain how dioxins are formed, which plastic type they are linked to and why they are harmful to humans.

Burning of PVC releases dioxins.Dioxins are very toxic to humans, because they cause skin, liver problems and affect nervous, endocrine and reproductive systems.

4. Yugaa wants to buy a plastic water bottle. She goes to the shop and sees four different kinds of plastic bottles with resin codes 1, 3, 5 and 7. Which one should she buy? Why?

Resin cods 1,3,7 are harmful plastics but resin code 5 is PP(poly propylene). It is a safer plastic. Therefore she should buy the plastic bottle with resin code 5.

VII. Answer the following by rearranging the jumbled letters.

1. It is the hardest allotrope of carbon.


Ans: diamond

2. Organic compounds having double bond between carbon atoms are


Ans: alkenes

3. Reaction of carbon with oxygen gives


Ans: oxides

4. In this molecule, carbon is attached with four hydrogen atoms.


Ans: methane

5. Carbon combines with other elements through _______ bond.


Ans: Covalent

6. It is used as gun powder.


Ans : Charcoal

7. Plastics made of _________ are represented by resin code #6.


Ans: polystyrene

8. One-time use plastics are also known as ____________ plastics.


Ans: throwaway

9. One-time use plastics cause ____________ damage.


Ans: environment

10. Expanded polystyrene is commercially known as


Ans: thermocol

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Last Updated: 3rd July 2023