2.Carbon and Its Compounds chapter):

Very Short Answer Type Questions (VSATQs) with answers, suitable for Class 10 CBSE Chemistry (based on Carbon and Its Compounds chapter):

1. Write the molecular formula of ethanol.

Answer: C₂H₅OH

2. What is the next higher homologue of methanol (CH₃OH)?

Answer: Ethanol (C₂H₅OH)

3. Identify the functional group present in the following compound and name it according to IUPAC system: CH₃OH

Answer: Functional group –OH (Hydroxyl group); IUPAC name: Methanol

4. Give the common name and IUPAC name of the simplest aldehyde.

Answer:
Common name: Formaldehyde
IUPAC name: Methanal

5. What is the common name of methanal?

Answer: Formaldehyde

6. Write the names of the following functional groups:

(a) –C≡C– → Alkyne
(b) –CO– (carbonyl group between two alkyl groups) → Ketone

7. Name the simplest ketone.

Answer: Propanone (also known as acetone)

8. What is the common name of propanone?

Answer: Acetone

9. Write the IUPAC names of the following:

(i) CH₃COCH₃ → Propanone
(ii) CH₃COCH₂CH₃ → Butanone

10. Write the name and chemical formula of the simplest organic acid.

Answer: Methanoic acid (HCOOH)

11. Write the IUPAC names, common names, and formulae of the first two members of the homologous series of carboxylic acids.

Answer:

Methanoic acid (Formic acid), Formula: HCOOH
Ethanoic acid (Acetic acid), Formula: CH₃COOH

12. What is the common name of:

(a) HCOOH → Formic acid
(b) CH₃COOH → Acetic acid

13. Draw the structures for the following compounds:

(a) Methanoic acid → H–COOH
(b) Ethanoic acid → CH₃–COOH

14. Give the common names and IUPAC names of the following compounds:

(a) HCOOH

Common Name: Formic acid
IUPAC Name: Methanoic acid
(b) CH₃COOH
Common Name: Acetic acid
IUPAC Name: Ethanoic acid

15. Give the name and structural formula of one homologue of HCOOH.

Answer: Ethanoic acid (CH₃COOH)

16. Write the formulae of:

(a) Methanoic acid → HCOOH
(b) Ethanoic acid → CH₃COOH

17. Give the common name and IUPAC name of C₂H₅OH.

Answer:
Common Name: Ethyl alcohol
IUPAC Name: Ethanol

18. Give the IUPAC name of the following compound: C₃H₇OH

Answer: Propanol

19. Give the name and structural formula of one member of the following: Alcohols

Answer: Ethanol, CH₃CH₂OH

20. Give IUPAC names of the following compounds:

(a) C₄H₉OH → Butanol
(b) CH₃OH → Methanol

21. What is the common name of methanol?

Answer: Wood alcohol

22. What is the difference between two consecutive homologues:

(i) In terms of molecular mass?
Answer: 14 u (CH₂ group)
(ii) In terms of number and kind of atoms per molecule?
Answer: Each successive member differs by one –CH₂– unit.

23. What type of fuels:

(a) Burn with a flame?
Answer: Gaseous fuels (e.g., LPG, methane)
(b) Burn without a flame?
Answer: Solid fuels (e.g., charcoal)

24. State whether the following statement is true or false:

The minimum number of carbon atoms in a ketone molecule is two.
Answer: False (Minimum is three carbon atoms as in propanone)

25. Fill in the following blanks with suitable words:

(a) The next higher homologue of ethanol is → Propanol
(b) The next homologue of C₂H₅OH is → C₃H₇OH (Propanol)
(c) The next higher homologue of ethane is → Propane
(d) The functional group present in ethanol is → –OH (Hydroxyl group)
(e) Organic compounds having –C–OH functional group are known as → Alcohols

Short Answer Questions with Answers for Class 10 CBSE Chapter "Carbon and Its Compounds" (

26 to 35):

26. Homologous Series and Molecular Formulae

(a)
Q: Give the general name of the class of compounds having the general formula CₙH₂ₙ₂. Write the name of the first member of this homologous series.
A: The general name is alkanes. The first member is methane (CH₄).

(b)
Q: The general formula of a homologous series is CₙH₂ₙ. Write the molecular formulae of the second and fourth members.
A:

Second member: C₂H₄ (Ethene)
Fourth member: C₄H₈ (Butene)

(c)
Q: Write the molecular formulae of the third and fifth members of the homologous series CₙH₂ₙ₊₂.
A:

Third member: C₃H₈ (Propane)
Fifth member: C₅H₁₂ (Pentane)

27. Homologues and Series Identification

(a)
Q: Give names and structural formulae of the next two higher homologues of methane.
A:

Ethane (C₂H₆): CH₃–CH₃
Propane (C₃H₈): CH₃–CH₂–CH₃

(b)
Q: The molecular formula of a hydrocarbon is C₁₀H₁₈. Name its homologous series.
A: The formula fits the general formula of alkynes (CₙH₂ₙ₋₂). So it belongs to the alkyne series.

(c)
Q: Select the hydrocarbons that are members of the same homologous series:
C₅H₁₀, C₃H₈, C₆H₁₀, C₄H₁₀, C₇H₁₂, C₈H₁₆
A:

C₅H₁₀, C₆H₁₀, C₇H₁₂ → Alkenes (CₙH₂ₙ)
C₃H₈, C₄H₁₀ → Alkanes (CₙH₂ₙ₊₂)
C₈H₁₆ → Alkene

28. Homologues and Mass Differences

(a)
Q: Give the molecular formula of one homologue of:
(i) C₃H₆ → C₄H₈
(ii) C₂H₆ → C₃H₈
(iii) C₂H₂ → C₃H₄

(b)
Q: What is the difference in molecular mass of any two adjacent homologues?
A: 14 u (CH₂ group)

(c)
Q: By how many carbon and hydrogen atoms do any two adjacent homologues differ?
A: By 1 carbon atom and 2 hydrogen atoms.

29. Functional Groups

(a)
Q: Write the formula of the functional group present in carboxylic acids.
A: –COOH

(b)
Q: Name the functional group present in CH₃–C≡CH.
A: Alkyne group

(c)
Q: Name the functional groups in:
(i) CH₃CHO → Aldehyde
(ii) CH₃CH₂COOH → Carboxylic acid
(iii) CH₃COCH₃ → Ketone
(iv) CH₃CH₂CH₂OH → Alcohol

30. Haloalkanes and Structures

(a)
Q: Write IUPAC and common name of CH₃Cl.
A:

IUPAC: Chloromethane
Common name: Methyl chloride

(b)
Q: Draw the structure of chlorobutane.
A: CH₃–CH₂–CH₂–CH₂Cl

(c)
Q: Draw structure for bromopentane. Are structural isomers possible?
A:
Yes. Structural isomers include:

1-bromopentane: CH₃–CH₂–CH₂–CH₂–CH₂Br
2-bromopentane: CH₃–CH₂–CHBr–CH₂–CH₃
3-bromopentane: CH₃–CHBr–CH₂–CH₂–CH₃

31. Ketones and Chloroalkanes

(a)
Q: Name and formula of a compound with a ketone group.
A: Propanone (CH₃COCH₃)

(b)
Q: First three members of chloroalkanes.
A:

Chloromethane (CH₃Cl)
Chloroethane (C₂H₅Cl)
1-Chloropropane (C₃H₇Cl)

(c)
Q: Name the compound CH₃CH₂Br.
A: Bromoethane

32. Functional Group Identification

(a)
Q: General name of compounds with –OH group?
A: Alcohols

(b)
Q: Which has carboxylic acid group?

CH₃OH
CH₃CHO
CH₃COOH ✅
CH₃COCH₃

(c)
Q: Name the compound: HCOOH
A: Methanoic acid (Formic acid)

33. Homologous Series and Alcohols

(a)
Q: Define homologous series. Give a homologue of CH₃OH.
A:
A homologous series is a group of organic compounds with the same functional group and similar chemical properties, differing by a –CH₂– unit.
Homologue of CH₃OH: C₂H₅OH (ethanol)

(b)
Q: Molecular formula of 3rd member of CₙH₂ₙ₊₁OH?
A: C₄H₉OH (Butanol)

(c)
Q: Name any two fossil fuels.
A: Coal and Petroleum

34. Structures and Naming

(a)
Q: Draw structures:

Propanone: CH₃COCH₃
Butanone: CH₃COCH₂CH₃

(b)
Q: IUPAC names:
(i) HCHO → Methanal
(ii) CH₃CHO → Ethanal
(iii) CH₃CH₂CHO → Propanal
(iv) CH₃CH₂CH₂CHO → Butanal

(c)
Q: What group is likely in C₄H₁₀O?
A: Alcohol group. Example: Butanol

35. Matching, Structure & Functional Group

(a)
Match:

CH₃COOH → Ethanoic acid
CH₃CHO → Ethanal
CH₃OH → Methanol

(b)
Draw Butanoic acid: CH₃CH₂CH₂COOH

(c)
Q: IUPAC name of acetic acid?
A: Ethanoic acid

36.

Q: Functional group in C₅H₁₀O₂?
A: Likely a carboxylic acid or ester. Example: Pentanoic acid (CH₃(CH₂)₃COOH)

(b)
Give examples:
(i) Aldehyde: CH₃CHO
(ii) Alcohol: CH₃OH
(iii) Carboxylic acid: CH₃COOH
(iv) Halo: CH₃Cl

(c)
Alkene: C₂H₄
Alkyne: C₂H₂

37. Alcohol from Pentane and Functional Groups

(a)
Q: Molecular formula and structure of alcohol from pentane?
A: C₅H₁₂O (Pentanol), structure: CH₃CH₂CH₂CH₂CH₂OH

(b)
Functional groups:
(i) –CHO → Aldehyde
(ii) –OH → Alcohol
(iii) –COOH → Carboxylic acid
(iv) C=O → Carbonyl group (Ketone or Aldehyde)
(v) –X → Halo group

(c)
Q: What makes the candle flame yellow and luminous?
A: Incomplete combustion of carbon produces soot (carbon particles), which glow and give yellow color.

Fgh Here are the Long Answer Type Questions with answers for Class 10 CBSE – Carbon and Its Compounds, covering questions 38, 39, and 40:

38. (a) What is a homologous series? Explain with an example.

Answer:
A homologous series is a group of organic compounds having the same functional group and similar chemical properties, in which the members differ by a -CH₂- group or 14 u (atomic mass units) in their molecular masses.
Example:
The alkane series:

Methane: CH₄
Ethane: C₂H₆
Propane: C₃H₈
Each successive member differs by –CH₂–.

(b) State two characteristics of a homologous series.

Answer:

All members have the same functional group and similar chemical properties.
Any two successive members differ by a –CH₂– unit and 14 u in molecular mass.

(c) The molecular formula of an organic compound is C₁₈H₃₆. Name its homologous series.

Answer:
The general formula of alkanes is CₙH₂ₙ₊₂.
However, for C₁₈H₃₆, the general formula is CₙH₂ₙ, which corresponds to alkenes.
So, C₁₈H₃₆ belongs to the alkene homologous series.

(d) Select the hydrocarbons which belong to the same homologous series. Give the name of each series.

Given hydrocarbons:
C₂H₂, C₂H₄, C₂H₆, C₄H₁₀, C₃H₄, C₃H₆, CH₄

Answer:

Alkanes (general formula: CₙH₂ₙ₊₂):
CH₄, C₂H₆, C₄H₁₀
Alkenes (general formula: CₙH₂ₙ):
C₂H₄, C₃H₆
Alkynes (general formula: CₙH₂ₙ₋₂):
C₂H₂, C₃H₄

Homologous series:

Alkanes: CH₄, C₂H₆, C₄H₁₀
Alkenes: C₂H₄, C₃H₆
Alkynes: C₂H₂, C₃H₄

(e) What is meant by 'heteroatom'? Give examples. Write the names and formulae of two organic compounds containing different heteroatoms.

Answer:
A heteroatom is an atom other than carbon and hydrogen that is present in an organic compound and replaces one or more hydrogen atoms.

Examples of heteroatoms: Oxygen (O), Nitrogen (N), Sulphur (S), Halogens (Cl, Br, etc.)

Compounds containing different heteroatoms:

Ethanol – C₂H₅OH (contains oxygen)
Chloroethane – C₂H₅Cl (contains chlorine)

39. (a) What is meant by a functional group? Explain with an example.

Answer:
A functional group is an atom or group of atoms in an organic molecule that gives the molecule its characteristic chemical properties.
Example:
In ethanol (C₂H₅OH), the –OH group is the functional group responsible for its alcohol properties.

(b) Write three common functional groups present in organic compounds. Give their symbols/formulae.

Answer:

Alcohol –OH
Carboxylic acid –COOH
Aldehyde –CHO

(c) Name the functional groups present in the following compounds:

(i) CH₃COOH – Carboxylic acid (–COOH)
(ii) CH₃CH₂CHO – Aldehyde (–CHO)
(iii) C₂H₅OH – Alcohol (–OH)
(iv) CH₃COCH₂CH₃ – Ketone (–CO–)

(d) Name the functional group which always occurs in the middle of a carbon chain.

Answer:
Ketone (–CO–) is the functional group that always occurs in the middle of the carbon chain.

(e) Draw the structures for the following compounds:

(i) Ethanal (CH₃CHO):

H   H  
 |   |  
H–C–C=O  
     |  
     H

(ii) Propanal (CH₃CH₂CHO):

CH₃–CH₂–CHO

(iii) Butanal (CH₃CH₂CH₂CHO):

CH₃–CH₂–CH₂–CHO

(iv) Pentanal (CH₃CH₂CH₂CH₂CHO):

CH₃–CH₂–CH₂–CH₂–CHO

40. (a) What happens when carbon burns in air? Write the chemical equation of the reaction which takes place.

Answer:
When carbon burns in air, it reacts with oxygen to form carbon dioxide and releases heat and light.

Chemical Equation:
C + O₂ → CO₂ + heat and light

(b) Why are coal and petroleum called fossil fuels?

Answer:
Coal and petroleum are called fossil fuels because they were formed from the remains of ancient plants and animals buried under the earth over millions of years.

(c) Explain how coal was formed in the earth.

Answer:
Coal was formed from the dead plants that accumulated in swampy forests about 300 million years ago. These remains were buried under soil and rock, and over time, heat and pressure converted them into coal.

(d) Describe how petroleum was formed in the earth.

Answer:
Petroleum was formed from the remains of tiny marine plants and animals buried under the ocean floor. Over millions of years, heat and pressure converted these remains into crude oil and natural gas, trapped in rock layers.

(e) Name a fossil fuel other than coal and petroleum.

Answer:
Natural gas is a fossil fuel other than coal and petroleum.

Letunder the ocean floor. Over millions of years, heat and pressure converted these remains into crude oil and natural gas, trapped in rock layers.

(e) Name a fossil fuel other than coal and petroleum.

Answer:
Natural gas is a fossil fuel other than coal and petroleum.

Multiple Choice Questions (MCQs 41–55) along with their correct answers and explanations:

41. The molecular formula of a homologue of butane is:

(a) C₄H₈
(b) C₃H₆
(c) C₄H₆
(d) C₃H₈ ✅ Correct Answer

✅ Answer: (d) C₃H₈

Explanation:
Butane (C₄H₁₀) belongs to the alkane series (general formula: CₙH₂ₙ₊₂). Its homologues differ by a -CH₂ group.
So, one lower homologue is C₃H₈ (propane) and one higher is C₅H₁₂ (pentane).
The other options (C₄H₈, C₄H₆, C₃H₆) do not follow the alkane formula.

42. One of the following molecular formulae can represent two organic compounds having different functional groups. This formula is:

(a) C₅H₁₂O ✅ Correct Answer
(b) C₅H₁₀O
(c) C₅H₁₀O₂
(d) C₅H₁₂

✅ Answer: (a) C₅H₁₂O

Explanation:
C₅H₁₂O can represent both alcohols and ethers, which are functional isomers.
e.g.,

Alcohol: CH₃CH₂CH₂CH₂CH₂OH
Ether: CH₃CH₂OCH₂CH₃

Other options are not functional isomers.

43. The number of carbon atoms in the molecule of the fifth member of the homologous series of alkynes is:

(a) four
(b) five
(c) six ✅ Correct Answer
(d) seven

✅ Answer: (c) six

Explanation:
General formula for alkynes: CₙH₂ₙ₋₂
Members:
1st → C₂H₂ (ethyne)
2nd → C₃H₄
3rd → C₄H₆
4th → C₅H₈
5th → C₆H₁₀ → 6 carbon atoms

44. One of the following burns without producing a flame. This is:

(a) wood
(b) charcoal ✅ Correct Answer
(c) LPG
(d) candle

✅ Answer: (b) charcoal

Explanation:
Charcoal burns with a glow and no flame because it lacks volatile substances.
Wood, LPG, and candles produce flames due to vaporized hydrocarbons.

45. The functional group which always occurs in the middle of a carbon chain is:

(a) alcohol group
(b) aldehyde group
(c) carboxyl group
(d) ketone group ✅ Correct Answer

✅ Answer: (d) ketone group

Explanation:
A ketone group (−CO−) is always between two carbon atoms in the chain.
In contrast, aldehydes (−CHO) and carboxylic acids (−COOH) are terminal groups.

46. The molecular formulae of some organic compounds are given. Which contains an aldehyde group?

(a) C₃H₈O
(b) C₃H₆O₂
(c) C₃H₆O ✅ Correct Answer
(d) C₃H₂Cl

✅ Answer: (c) C₃H₆O

Explanation:
C₃H₆O can be propanal (aldehyde) or acetone (ketone)—both isomers.
So, it can represent an aldehyde.
C₃H₈O is alcohol (e.g., propanol), not aldehyde.

47. The organic compounds which are isomeric with one another are:

(a) alcohols and aldehydes
(b) aldehydes and carboxylic acids
(c) ketones and aldehydes ✅ Correct Answer
(d) alcohols and ketones

✅ Answer: (c) ketones and aldehydes

Explanation:
Aldehydes and ketones with the same molecular formula can be functional isomers.
e.g., Propanal (aldehyde) and acetone (ketone): both C₃H₆O

48. The fuel which usually burns with a blue flame is:

(a) coal
(b) LPG ✅ Correct Answer
(c) candle wax
(d) kerosene (in lamp)

✅ Answer: (b) LPG

Explanation:
LPG (liquefied petroleum gas) is a clean-burning fuel and gives a blue flame indicating complete combustion.
Coal and kerosene may give yellow flames due to incomplete combustion.

49. Which of the following burns by producing a yellow, luminous flame?

(a) natural gas
(b) coke
(c) wax ✅ Correct Answer
(d) charcoal

✅ Answer: (c) wax

Explanation:
Wax (candle) produces a bright yellow luminous flame due to incomplete combustion of carbon particles.
Coke and charcoal burn with little or no flame.

50. The molecular formula C₄₈H₉₄ belongs to the homologous series of:

(a) alkenes
(b) aldehydes
(c) alkynes
(d) alkanes ✅ Correct Answer

✅ Answer: (d) alkanes

Explanation:
General formula for alkanes: CₙH₂ₙ₊₂
For C₄₈ → H = 2×48 + 2 = 98 → C₄₈H₉₈
But given H = 94 → 4 less H = 2 double bonds or 1 triple bond, so not alkane
Wait: Correction Needed

✅ Correct Answer should be: None of the above (but among given, most likely alkenes)

New ✅ Answer: (a) alkenes

Explanation (corrected):
Alkenes: General formula CₙH₂ₙ
Check: For C₄₈ → H = 96
Given H = 94 → missing 2 H → one double bond → it's an alkene

51. One of the following molecular formulae represents a ketone. This is:

(a) C₅H₁₂O
(b) C₆H₁₂O₂
(c) C₆H₁₄O
(d) C₆H₁₂O ✅ Correct Answer

✅ Answer: (d) C₆H₁₂O

Explanation:
C₆H₁₂O can represent a ketone, e.g., hexan-3-one.
Alcohols and ethers can have C₆H₁₂O too, but only ketones match the functional group.
The others do not necessarily represent ketones.

52. Which one of the following is not a fossil fuel?

(a) petrol
(b) coke
(c) charcoal ✅ Correct Answer
(d) coal

✅ Answer: (c) charcoal

Explanation:
Charcoal is produced by burning wood in limited air—not formed from fossils.
The others (coal, coke, petrol) are fossil fuels.

53. Butanone is a four-carbon compound having the functional group:

(a) −COOH
(b) −CHO
(c) −CO− ✅ Correct Answer
(d) −OH

✅ Answer: (c) −CO−

Explanation:
Butanone is a ketone with the −CO− group located within the carbon chain.
It’s not an alcohol (−OH), acid (−COOH), or aldehyde (−CHO).

54. The molecular formula of the third member of the homologous series of ketones is:

(a) C₄H₈O
(b) C₃H₆O
(c) C₅H₁₀O ✅ Correct Answer
(d) C₆H₁₂O

✅ Answer: (c) C₅H₁₀O

Explanation:
Ketone series: General formula CₙH₂ₙO
Members:
1st → C₃H₆O
2nd → C₄H₈O
3rd → C₅H₁₀O

55. The functional group present in propanal is:

(a) −OH
(b) −COOH
(c) −CO−
(d) −CHO ✅ Correct Answer

✅ Answer: (d) −CHO

Explanation:
Propanal is an aldehyde (ends with −al) and contains the −CHO group.

questions and detailed answers for Class 10 CBSE based on HOTS / Case-Based Questions related to Carbon and Its Compounds:

56. Isomers of C₃H₆O with Different Functional Groups

Case:
An organic compound with molecular formula C₃H₆O can form two isomers, A and B. Isomer A is a liquid used in nail polish remover. Isomer B is also a liquid. A lower homologue of B is used to preserve biological specimens.

(a) What is compound A?
Answer: Compound A is propanone (acetone).

(b) Write the electron-dot structure of A.
Answer:

       O
       ||
H3C — C — CH3

Electron-dot structure shows shared electron pairs around each atom (omitted here for brevity but can be provided if required).

(c) What is compound B?
Answer: Compound B is propanal.

(d) Write the electron-dot structure of B.
Answer:

    H   H   O
    |   |  ||
H — C — C — C — H
        |
        H

(e) Name the lower homologue of compound B used to preserve biological specimens.
Answer: The compound is formaldehyde (HCHO).

57. Fuels and Their Combustion Properties

Case:
Material X is hard and mined from earth (used in thermal power plants), Y is soft and used in candles, Z is gaseous and used in CNG form.

(a) What are materials X, Y and Z?
Answer:

X = Coal
Y = Wax
Z = Methane (CNG)

(b) When burned separately:

(i) Which material burns by producing a yellow, luminous flame?
Answer: Y (Wax)

(ii) Which material ultimately burns without producing a flame?
Answer: X (Coal)

(iii) Which material burns in a gas stove with a blue flame?
Answer: Z (Methane / CNG)

58. Identifying Organic Compounds by Formula

Given:

A = C₄H₈O₂
B = C₄H₁₀O
C = C₄H₈O

(a) Which contains an alcohol group? Name & structural formula.
Answer:

Compound B
Name: Butanol
Structure: CH₃–CH₂–CH₂–CH₂OH or CH₃–CH(OH)–CH₂–CH₃

(b) Which contains a carboxyl group? Name & structural formula.
Answer:

Compound A
Name: Butanoic acid
Structure: CH₃–CH₂–CH₂–COOH

(c) Which molecular formula can represent an aldehyde and a ketone?
Answer:

Compound C (C₄H₈O)
Aldehyde: Butanal → CH₃–CH₂–CH₂–CHO
Ketone: Butanone → CH₃–CO–CH₂–CH₃

59. Identifying Liquids Based on Formula and Use

(a) Name X. Series and one more member.
Answer:

Name: Acetic acid
Series: Carboxylic acids
Another member: Formic acid (HCOOH)

(b) Name Y. Series and one more member.
Answer:

Name: Propanone
Series: Ketones
Another member: Butanone

(c) Same formula as Y but different series? Name and series.
Answer:

Name: Propanal (isomer of propanone)
Series: Aldehydes

(d) Name Z. Series and one more member.
Answer:

Name: Ethanol
Series: Alcohols
Another member: Methanol

60. Derivatives of Propane (C₃H₈)

(a) Replace 1 H by Cl:

Name: Chloropropane
Formula: C₃H₇Cl

(b) Replace 1 H by OH:

Name: Propanol
Formula: C₃H₇OH

(c) Replace 1 H by CHO group:

Name: Propanal
Formula: CH₃–CH₂–CHO

(d) Replace 1 H by COOH group:

Name: Propanoic acid
Formula: CH₃–CH₂–COOH

(e) Replace two H from middle carbon by 1 O:

Name: Propanone (Acetone)
Formula: CH₃–CO–CH₃