MP Board Solutions for Class 10 Science Chapter 4 – Carbon and its Compounds

Carbon and Its Compounds – Important Questions with Answers

1. Explain catenation and why carbon exhibits this property.
Answer: Catenation is the ability of an element to form chains with itself by covalent bonds. Carbon exhibits strong C–C bonds, allowing long chains and rings, leading to immense compound diversity.

2. Define hydrocarbons and name two types with examples.
Answer: Hydrocarbons are organic compounds made of hydrogen and carbon only. Two types are alkanes (e.g., methane CH₄) and alkenes (e.g., ethene C₂H₄), differing in bonding.

3. What is isomerism? Provide an example from carbon compounds.
Answer: Isomerism is when compounds have same molecular formula but different structures and properties. For instance, C₄H₁₀ has two isomers: n-butane (chain) and isobutane (branched).

4. Explain functional groups and name three in organic chemistry.
Answer: Functional groups are specific atomic patterns within molecules responsible for chemical behavior. Examples include hydroxyl (–OH in alcohols), carbonyl (C=O in aldehydes/ketones), and carboxyl (–COOH in acids).

5. Describe homologous series with an example.
Answer: Homologous series are families of compounds differing by CH₂ units but having similar properties, like alkanes (CH₄, C₂H₆, C₃H₈…). Successive members differ by constant mass and structure patterns.

6. Why are carbon compounds often combusted? What are products of complete combustion?
Answer: Carbon compounds combust because C–H bonds release energy when burning in oxygen. Complete combustion yields carbon dioxide (CO₂) and water (H₂O), with heat released.

7. Differentiate between saturated and unsaturated hydrocarbons with examples.
Answer: Saturated hydrocarbons contain only single C–C bonds, like alkanes (methane, ethane), while unsaturated hydrocarbons have double or triple bonds, like ethene (alkene) or acetylene (alkyne).

8. Explain oxidation of ethanol and products formed.
Answer: Ethanol oxidizes to acetic acid when partially oxidized via warm acidified potassium permanganate; further oxidation yields CO₂ & H₂O. Partial oxidation used in vinegar formation.

9. Give the chemical reaction for fermentation of glucose. Name product and its uses.
Answer: Yeast converts glucose into ethanol and CO₂: C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂. Ethanol is used in alcoholic beverages, antiseptics, and biofuel, while CO₂ helps breads rise.

10. Describe substitution reaction in methane with chlorine.
Answer: Methane reacts with chlorine under UV light, replacing a hydrogen atom by chlorine to yield chloromethane and hydrogen chloride: CH₄ + Cl₂ → CH₃Cl + HCl.

11. Define homolog and write molecular formula for fifth member of alkane series.
Answer: Homologs differ by CH₂ in a series. The fifth alkane after methane, ethane, propane, and butane is pentane: C₅H₁₂.

12. How are alcohols and carboxylic acids derived from hydrocarbons?
Answer: Alkanes can be oxidized to primary alcohols (R–OH), which further oxidize to aldehydes and then to carboxylic acids (R–COOH), utilizing catalysts or reflux conditions.

13. Give one use each of ethanol and ethanoic acid.
Answer: Ethanol is used in alcoholic drinks, fuels, and disinfectants. Ethanoic acid (acetic acid) is used in vinegar for cooking, as a preservative, and in industrial chemical synthesis.

14. Define hydration reaction with example.
Answer: Hydration adds water across a double bond of an alkene. Ethene reacts with steam: C₂H₄ + H₂O → C₂H₅OH in presence of acid catalyst to form ethanol.

15. Explain why carbon forms four covalent bonds.
Answer: Carbon has four valence electrons and wants four more to complete its octet. Thus, it forms four single covalent bonds, achieving stability by sharing electrons.

16. What is polymerization? Provide an example of a synthetic polymer.
Answer: Polymerization is joining many small molecules (monomers) into large macromolecules (polymers). Example: Ethene monomers polymerize to form polyethylene, used in plastic bags and containers.

17. Discuss environmental issues related to plastics and one possible mitigation.
Answer: Plastics are non-biodegradable, polluting land and oceans, harming wildlife and humans through microplastics. Mitigation includes recycling, plastic bans, and using biodegradable alternatives or compostable bioplastics.

18. Explain the esterification reaction between ethanol and ethanoic acid.
Answer: In presence of concentrated sulfuric acid, ethanol and ethanoic acid react to form ethyl ethanoate (an ester) and water: C₂H₅OH + CH₃COOH → CH₃COOC₂H₅ + H₂O.

19. What are biofuels? Give example from carbon compounds.
Answer: Biofuels are renewable fuels derived from biomass. Ethanol produced by fermentation of sugarcane or corn is a common biofuel, used to blend with petrol, reducing greenhouse gas emissions.

20. How does fractional distillation separate crude oil?
Answer: Crude oil contains hydrocarbons with varying boiling points. Fractional distillation heats the mixture, separating lighter, more volatile fractions (like petrol) from heavier ones (like diesel, lubricating oil).

21. Justify why alcohols are more soluble in water than alkanes.
Answer: Alcohols contain polar –OH groups forming hydrogen bonds with water, increasing solubility. Alkanes are nonpolar hydrocarbons and do not mix, making them insoluble in water.

22. Explain dehydration of ethanol to ethene.
Answer: Ethanol, when heated with concentrated sulfuric acid, loses water forming ethene gas: C₂H₅OH → C₂H₄ + H₂O. This elimination reaction is used to produce ethene industrially.

23. Describe complete and incomplete combustion of ethanoic acid.
Answer: Complete combustion of ethanoic acid yields CO₂ and H₂O, releasing energy. Incomplete combustion in limited air produces carbon monoxide or soot (carbon), which is toxic and inefficient.

24. Define aromatic compound and give an example with structure.
Answer: Aromatic compounds contain stable ring structures with delocalized π-electrons. Benzene (C₆H₆) is a common example: a hexagonal ring with alternating double bonds, used in plastics and solvents.

25. Explain the difference between detergent and soap at chemical level.
Answer: Soaps are sodium or potassium salts of fatty acids; detergents are synthetic surfactants with diverse molecular structures. Detergents work in hard water, while soap forms scum with Ca²⁺/Mg²⁺ ions.