CBSE Class 10 Science Chapter 4 Carbon and its Compounds Important Questions

Science is one of the most important subjects in Class 10, and Chapter 4 Carbon and Its Compounds holds a special place in the syllabus. Students often look for carbon and its compounds class 10 important questions to prepare well for exams because this chapter carries a good weightage in the CBSE board exam. Practicing the important questions of carbon and its compounds class 10 not only helps in understanding the concepts better but also ensures full preparation for both short and long answer questions.

The chapter explains how carbon, being a versatile element, forms millions of compounds by sharing electrons. Students learn about covalent bonding, hydrocarbons, homologous series, nomenclature of organic compounds, and the properties of useful compounds such as ethanol and ethanoic acid. To master these topics, going through carbon and its compounds important questions is highly recommended. These questions include definitions, reasoning-based answers, chemical equations, and diagrams.

Every year, examiners set questions directly from this chapter. Solving previous year questions of carbon and its compounds class 10 pdf with answers helps students identify repeated topics and the type of questions expected in the board exam. Many times, the important questions from carbon and its compounds are similar to questions asked in earlier years, so focusing on them can save time and boost marks.

The set of class 10 carbon and its compounds important questions includes all categories of problems: 1-mark, 3-mark, and 5 marks questions on carbon and its compounds. While 1-mark questions are usually definitions or short examples, the long answer questions often demand detailed explanations with proper reactions and diagrams. Preparing these well ensures that students are ready to attempt any kind of problem in the exam.

To make revision easier, students can also refer to carbon and its compounds class 10 important questions with answers. These solved questions help in understanding the correct way of writing answers as per the CBSE marking scheme. This way, students can score better marks by presenting accurate reactions, equations, and diagrams.

Do Check: CBSE Class 10 Science Chapter 2 Important Questions

Carbon and its Compounds Important Questions (1 Mark)

Q1. Define allotropy of carbon.
Answer: The phenomenon in which an element exists in two or more different physical forms in the same physical state is called allotropy. Carbon shows allotropy in the form of diamond, graphite, and fullerene.

Q2. What type of bond is formed in carbon compounds?
Answer: Carbon compounds form covalent bonds by sharing electrons.

Q3. Give the general formula of alkanes.
Answer: The general formula of alkanes is CnH₂n+2.

Q4. Write the IUPAC name of CH₃CH₂OH.
Answer: Ethanol.

Q5. What is a homologous series?
Answer: A homologous series is a group of organic compounds having the same functional group and general formula, with successive members differing by –CH2– group.

Q6. What are alkenes? Write their general formula.
Answer: Hydrocarbons containing at least one double bond (C=C) are called alkenes. General formula: CnH2n.

Q7. Write the functional group of alcohols.
Answer: The functional group of alcohols is –OH (hydroxyl group).

Q8. Give one difference between soaps and detergents.
Answer: Soaps are sodium or potassium salts of fatty acids, while detergents are sodium salts of sulphonic acids.

Q9. Write the IUPAC name of CH3–CH2–COOH.
Answer: Propanoic acid.

Q10. Which allotrope of carbon is a good conductor of electricity? Why?
Answer: Graphite because it has free delocalized electrons that can move freely.

Q11. Write the formula of acetic acid.
Answer: CH3COOH.

Q12. State the type of bond formed in diamond.
Answer: Strong covalent bonds.

Do Check: CBSE Class 10 Science Important Questions

Class 10 Carbon and its Compounds Important Questions (3 Marks)

Q1. Differentiate between saturated and unsaturated hydrocarbons.
Answer:

• Saturated hydrocarbons: Contain only single bonds (C–C). Example: methane (CH₄).
• Unsaturated hydrocarbons: Contain double (C=C) or triple bonds (C≡C). Example: ethene (C₂H₄), ethyne (C₂H₂).
• Saturated hydrocarbons are less reactive, while unsaturated hydrocarbons are more reactive.

Q2. Why are detergents better than soaps in hard water?
Answer:

• Soaps form insoluble precipitates (scum) with calcium and magnesium salts present in hard water.
• Detergents do not form scum and remain effective in hard water.
• Hence, detergents are preferred for washing in both soft and hard water.

Q3. Write any three properties of carbon compounds.
Answer:

1. They form covalent bonds.
2. They have low melting and boiling points compared to ionic compounds.
3. They are generally poor conductors of electricity due to the absence of free ions.

Q4. Write three differences between ionic and covalent compounds.
Answer:

1. Ionic compounds are formed by transfer of electrons, covalent by sharing.
2. Ionic compounds are soluble in water, covalent mostly insoluble.
3. Ionic compounds conduct electricity in solution, covalent compounds do not.

Q5. State three characteristics of homologous series.
Answer:

1. Same functional group and chemical properties.
2. Successive members differ by –CH2– group and 14 u molecular mass.
3. Gradation in physical properties like melting/boiling points.

Do Check: NCERT Solutions for Class 10 Science

Q6. Why does carbon form covalent bonds?
Answer:

• Carbon has 4 electrons in its outermost shell.
• It cannot lose 4 electrons (requires high energy) or gain 4 electrons (unstable).
• Hence, it shares electrons to achieve stability — forming covalent bonds.

Q7. Write three physical properties of ethanol.
Answer:

1. Colorless liquid with characteristic smell.
2. Miscible in water in all proportions.
3. Has lower density than water.

Q8. Why is diamond hard while graphite is soft and slippery?
Answer:

• In diamond, each carbon atom is bonded to 4 other atoms in a rigid 3D network → very hard.
• In graphite, each carbon is bonded to 3 others in layers with weak forces between them → soft and slippery.

Q9. Write any three uses of ethanoic acid.
Answer:

1. Used in vinegar as a preservative.
2. Used in production of esters (perfumes).
3. Used in manufacture of plastics and dyes.

Q10. Why is homologous series important in organic chemistry?
Answer:

• Predicts properties of compounds.
• Makes systematic study easier.
• Allows classification of millions of organic compounds.

Q11. What happens when ethanol is heated with concentrated H₂SO₄?
Answer: It gets dehydrated to form ethene:

Important Questions of Carbon and its Compounds Class 10 (5 Marks)

Q1. Write the physical and chemical properties of ethanol with equations.
Answer:

Physical properties:

• Colorless liquid, soluble in water.
• Has a characteristic smell.

Chemical properties:

1. Reaction with sodium:
   $2C2H5OH + 2Na → 2C2H5ONa + H2 ↑$
2. Dehydration to give ethene:

Do Check: CBSE Class 10 Science Sample Papers

Q2. Write the physical and chemical properties of ethanoic acid with equations.
Answer:

Physical properties:

• Colorless liquid with a strong smell (vinegar).
• Soluble in water.

Chemical properties:

1. Reaction with sodium carbonate:
   $2CH3COOH + Na2CO3 → 2CH3COONa + H2O + CO2 ↑$
2. Reaction with sodium hydroxide (neutralization):

Q3. Explain the structure and cleaning action of soap micelles.
Answer:

• Soap molecules have hydrophobic (water-repelling) tails made of hydrocarbons and hydrophilic (water-attracting) heads.
• In water, soap molecules arrange into micelles with tails inside and heads outside.
• The tail traps oily dirt, while the head remains in water, allowing soap to wash away dirt effectively.

Q4. Explain homologous series with examples.
Answer:

• A homologous series is a group of organic compounds with the same functional group and general formula, differing by –CH₂– group.
• Properties:
  1. Gradation in physical properties (like boiling point).
  2. Similar chemical properties.
• Examples:
  • Alkanes: CH₄, C₂H₆, C₃H₈ (general formula CnH₂n+2).
  • Alcohols: CH₃OH, C₂H₅OH, C₃H₇OH (general formula CnH₂n+1OH).

Q5. Explain the structure of diamond, graphite, and fullerene with diagrams.
Answer:

• Diamond: Each carbon atom bonded to 4 others in a tetrahedral structure, very hard.
• Graphite: Each carbon atom bonded to 3 others in hexagonal layers with free electrons, good conductor.
• Fullerene: Spherical structure (like a football) with 60 carbon atoms (C60).

Q6. Explain the process of saponification with chemical equation.
Answer:

• Saponification is the process of preparing soap by heating fats or oils with sodium hydroxide (NaOH).
• Reaction: (Fats + NaOH → Glycerol + Soap)

Do Check: CBSE Class 10 Science Syllabus

Q7. Write the differences between soaps and detergents with chemical explanation.
Answer:

1. Soaps are sodium salts of fatty acids, detergents are sodium salts of sulphonic acids.
2. Soaps form scum in hard water, detergents do not.
3. Detergents are more effective cleaning agents than soaps.

Q8. Explain why carbon is called a versatile element.
Answer:

• Tetravalency: Forms 4 bonds.
• Catenation: Forms long chains.
• Forms single, double, and triple bonds.
• Combines with other elements to form millions of compounds.