Std 10th Science Part 1 – Chapter 9 : Carbon Compounds Exercise Questions And Answers Maharashtra Board

Q1. Match the pairs.

Group ‘A’	Group ‘B’
a. C2​H6​	1. Unsaturated hydrocarbon
b. C2​H2​	2. Molecular formula of an alcohol
c. CH4​O	3. Saturated hydrocarbon
d. C3​H6​	4. Triple bond

Answer – 

Group ‘A’	Group ‘B’
a. C2​H6​	3. Saturated hydrocarbon
b. C2​H2​	4. Triple bond
c. CH4​O	2. Molecular formula of an alcohol
d. C3​H6​	1. Unsaturated hydrocarbon

Q2. Draw an electron dot structure of the following molecules. (Without showing the circles)

a. Methane (CH4​)

• Carbon shares its 4 valence electrons with 4 hydrogen atoms, forming 4 single covalent bonds.

b. Ethene (C2​H4​)

• Two carbon atoms share two pairs of electrons (a double bond) and each carbon shares electrons with two hydrogen atoms.

c. Methanol 

• The methyl group (CH3​) is bonded to the alcohol group (-OH). 

d. Water

• Oxygen shares its two unpaired electrons with two hydrogen atoms.

Q3. Draw all possible structural formulae of compounds from their molecular formula given below.

a. C_3​H₈​ (Propane)

Answer –

b. C_4​H₁₀​ (Butane)

Answer –

c. C₃​H₄​ (Propyne)

Answer –

Q4. Explain the following terms with example.

a. Structural isomerism

• Explanation: It is the phenomenon in which compounds have the same molecular formula but possess different structural formulae (different ways the atoms are connected).
• Example: C_4​H_10​ has two isomers: n-Butane and Isobutane (or 2-Methylpropane).

b. Covalent bond

• Explanation: A chemical bond formed by the sharing of two valence electrons between two atoms. This allows both atoms to achieve a stable noble gas electron configuration.
• Example: The bond between two hydrogen atoms in an H2​ molecule (H−H).

c. Hetero atom in a carbon compound

• Explanation: An atom of an element (other than carbon or hydrogen) that substitutes for a hydrogen atom in a hydrocarbon chain. These elements include oxygen, nitrogen, sulfur, or halogens.
• Example: In methanol (CH3​OH), Oxygen (O) is the hetero atom.

d. Functional group

• Explanation: A specific atom or a group of atoms containing a hetero atom that determines the specific chemical properties of a carbon compound, regardless of the length of the carbon chain.
• Example: The Alcohol group (-OH).

e. Alkane

• Explanation: Saturated hydrocarbons in which the valencies of all atoms are satisfied by single covalent bonds only. Their general formula is
  C_n​H_2n+2​.
• Example: Propane (C₃​H_8​).

f. Unsaturated hydrocarbon

• Explanation: Carbon compounds that contain a double bond (Alkenes) or a triple bond (Alkynes) between two carbon atoms. They are generally more reactive than saturated compounds.
• Example: Ethene (CH_2​=CH₂​).

g. Homopolymer

• Explanation: A macromolecule (polymer) formed by the regular repetition of a single type of monomer.
• Example: Polyethylene is formed from the monomer ethylene (CH₂​=CH₂​).

h. Monomer

• Explanation: The small repeating unit whose regular connection forms a large molecule called a polymer.
• Example: Ethylene (CH_2​=CH₂​) is the monomer for polyethylene.

i. Reduction

• Explanation (in terms of O/H): A chemical reaction in which a reactant gains hydrogen or loses oxygen to form the product.
• Example: Hydrogenation of vegetable oil.

j. Oxidant

• Explanation: A chemical substance that causes an oxidation reaction by either supplying oxygen or removing hydrogen from another substance.
• Example: Alkaline Potassium Permanganate (KMnO4​).

Q5. Write the IUPAC names of the following structural formulae.

a. CH₃ -CH₂ -CH₂ -CH₃

Answer –

• Parent : Butane (4 Carbons, Alkane)
• IUPAC Name : n-Butane

b. CH₃ -CHOH-CH₃

Answer –

• Parent: Propane. 
• Functional Group: -OH (Alcohol/ol). 
• Position: 2
• IUPAC Name: Propan-2-ol

c. CH₃ -CH₂ -COOH

Answer – 

• Parent: Propane. 
• Functional Group: -COOH (Carboxylic Acid/oic acid).
• IUPAC Name: Propanoic acid

d. CH₃​−CH₂​−NH₂​

Answer – 

• Parent : Ethane.
• Functional Group : -NH2​ (Amine/amine).
• IUPAC Name : Ethanamine

e. CH₃​−CHO

Answer – 

• Parent: Ethane.
• Functional Group: -CHO (Aldehyde/al).
• IUPAC Name: Ethanal

f. CH₃​−CO−CH_2​−CH_3​

Answer – 

• Parent: Butane.
• Functional Group: -CO- (Ketone/one).
• Position: 2
• IUPAC Name: Butan-2-one

Q6. Identify the type of the following reaction of carbon compounds.

a. CH_3​−CH_2​−CH_2​−OH  → ​CH₃​−CH_2​−COOH

Answer – 

• Type: Oxidation Reaction (Alcohol → Carboxylic Acid). 

b. CH_3​−CH₂​−CH₃​+5O₂ ​⟶ 3CO₂​+4H_2​O

Answer – Type : Combustion Reaction (Reactant combines with O2​ to release heat and light).

c. CH₃​−CH=CH−CH_3​ + Br₂​ ⟶ CH_3​−CHBr−CHBr−CH_3​

Answer – Type: Addition Reaction (Bromine adds across the double bond of the unsaturated compound).

d. CH₃​−CH₃​+Cl₂ ​⟶ CH_3​−CH₂​−Cl + HCl

Answer – Type: Substitution Reaction (A hydrogen atom is replaced by a chlorine atom).

e. CH_3​−CH_2​−CH₂​−CH₂​−OH ⟶ CH₃​−CH_2​−CH=CH₂​ + H₂​O

Answer – Type : Dehydration Reaction (Water molecule is removed, specifically an elimination reaction). This reaction is also a type of decomposition reaction where a single reactant forms two products.

f. CH_3​−CH_2​−COOH + NaOH ⟶ CH_3​−CH₂​−COO−Na⁺ + H₂​O

Answer – Type: Neutralization Reaction (Carboxylic acid reacts with a strong base to form salt and water).

g. CH₃​−COOH+CH_3​−OH ⟶ CH_3​−COO−CH_{3 ​}+ H₂​O

Answer – Type: Esterification Reaction (Carboxylic acid reacts with alcohol to form an ester and water).

Q7. Write structural formulae for the following IUPAC names.

a. pentan -2-one 

Answer – Ketone on the 2nd carbon of a 5-carbon chain.

b. 2-chlorobutane

Answer – Chlorine on the 2nd carbon of a 4-carbon chain.

c. propan-2-ol

Answer – Alcohol (-OH) on the 2nd carbon of a 3-carbon chain.

d. methanal

Answer – Aldehyde (-CHO) with 1 carbon (formaldehyde). 

e. butanoic acid

Answer – Carboxylic acid (-COOH) with 4 carbons.

f. 1-bromopropane

Answer – Bromine (-Br) on the 1st carbon of a 3-carbon chain.

Br−CH₂​−CH₂​−CH_3​

g. ethanamine

Answer – Amine (-NH2​) with 2 carbons. 

CH₃​−CH₂​−NH_2​

h. butanone

Answer – Ketone (-CO) with 4 carbons (only butan-2-one is possible).

Q8. Write answers as directed.

a. What causes the existence of very large number of carbon compound?

Answer – This is primarily due to the unique combination of the following two properties of the carbon atom:

1. Catenation: The ability of carbon atoms to form strong covalent bonds with other carbon atoms, leading to long chains, branched chains, or ring structures.
2. Tetravalency: Each carbon atom can form four bonds (single, double, or triple) with other carbon atoms or atoms of other elements (like O, N, S, halogens).
3. Isomerism: The possibility of different structures (isomers) for the same molecular formula increases the number of compounds.

b. Saturated hydrocarbons are classified into three types. Write these names giving one example each.

Answer – Saturated hydrocarbons are also called Alkanes.

1. Straight Chains: Carbon atoms are joined one after another.
   • Example: Propane (C₃​H_8​).
2. Branched Chains: The carbon chain has side chains or branches.
   • Example: Isobutane (or 2-methylpropane), an isomer of C₄​H_10​.
3. Ring Structures (Cyclic): Carbon atoms form a closed ring.

Example:Cyclohexane (C_6​H₁₂​).

c. Give any four functional groups containing oxygen as the heteroatom in it. Write name and structural formula of one example each.

Answer – 

d. Give names of three functional groups containing three different hetero atoms. Write name and structural formula of one example each.

Answer – 

e. Give names of three natural polymers. Write the place of their occurrence and names of monomers from which they are formed.

Answer – 

Natural Polymer	Monomer	Place of Occurrence
Proteins	Alpha amino acids	Muscles, hair, enzymes, skin
Cellulose	Glucose	Wood (cell walls of plant cells)
Rubber	Isoprene	Latex of rubber tree

f. What is meant by vinegar and gasohol? What are their uses?

Answer – 

• Vinegar: It is a 5−8% aqueous solution of Ethanoic Acid (or acetic acid).
  • Use: It is primarily used as a preservative in pickles.
• Gasohol: It is a fuel mixture consisting of ethanol and petrol.
  • Use: It is used as an additive to increase the efficiency of petrol in engines, as ethanol is a clean fuel.

g. What is a catalyst? Write any one reaction which is brought about by use of catalyst?

Answer – 

• Catalyst: A substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change.
• Example Reaction (Hydrogenation):
  • Vegetable oil reacts with hydrogen gas in the presence of a nickel (Ni) catalyst to form Vanaspati ghee (a saturated compound).

Unsaturated Oil + H_2​ ​⟶ Saturated Vanaspati Ghee