Class 10 chemistry important questions with answers are provided here for Chapter 4 Carbon and its Compounds. These important questions are based on the CBSE board curriculum and correspond to the most recent Class 10 chemistry syllabus. By practising these Class 10 important questions, students will be able to quickly review all of the ideas covered in the chapter and prepare for the Class 10 Annual examinations.
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Class 10 Chapter 4 Carbon and its Compounds Important Questions with Answers
Multiple Choice Type Questions
Q1. C3H8 belongs to the homologous series of
(a ) Alkynes
(b ) Alkenes
(c ) Alkanes
(d ) Cycloalkanes
Answer:
(c ), C3H8 belongs to the homologous series of alkanes.
Q2. Which of the following will undergo an addition reaction?
(a ) CH4
(b ) C3H8
(c ) C2H6
(d ) C2H4
Answer:
(d ) C2H4 is an alkene. Hence it will undergo an addition reaction.
Q3. In a diamond, each carbon atom is bonded to four other carbon atoms to form
(a ) A hexagonal array
(b ) A rigid three-dimensional structure
(c ) A structure in the shape of a football
(d ) A structure of a ring
Answer:
(b ), In a diamond, each carbon atom is bonded to four other carbon atoms to form a rigid three-dimensional structure.
Q4. The allotrope of carbon which is a good conductor of heat and electricity is
(a ) Diamond
(b ) Graphite
(c ) Charcoal
(d ) None of these
Answer:
(b ) The allotrope of carbon which is a good conductor of heat and electricity is graphite.
Q5. How many double bonds are there in a saturated hydrocarbon?
(a ) One
(b ) Two
(c ) Three
(d ) Zero
Answer:
(d ) A saturated hydrocarbon has zero double bonds.
Short Answer Type Questions
Q1. Draw the structural formula of ethyne.
Answer:
Structural Formula: H – C ≡ C – H
Q2. Write the names of the following compounds.
Answer:
(a ) Pentan-1-oic Acid
(b ) But-1-yne
(c ) Heptan-1-al
(d ) Pentan-1-ol
Q3. Identify and name the functional groups present in the following compounds.
Answer:
(a ) Propan-1-ol
(b ) Propan-1-oic Acid
(c ) Pent-3-one
(d ) But-1-ene
Q4. A compound X is formed by the reaction of carboxylic acid C2H4O2 and alcohol in the presence of a few drops of H2SO4. The alcohol on oxidation with alkaline KMnO4 followed by acidification gives the same carboxylic acid as used in this reaction. Give the names and structures of (a) carboxylic acid, (b) alcohol and (c) compound X. Also, write the reaction.
Answer:
Here, the carboxylic acid is ethanoic acid, alcohol is ethanol, and compound X is ethyl ethanoate.
Structure of Ethanoic Acid:
Structure of Ethanol:
Structure of Ethyl Ethanoate:
Reactions Involved:
CH3COOH + CH3CH2COOH → CH3COOC2H5 + H2O
C2H5OH + Alkaline KMnO4 → CH3COOH
Q5. Why are detergents better cleansing agents than soaps? Explain.
Answer:
Detergents are better cleansing agents than soaps because we can use them even with hard water. Detergents have a more decisive cleansing action than soaps and are more soluble in water than soaps. The charged ends of detergents do not form insoluble precipitates with calcium and magnesium ions in hard water. When soap is used for washing clothes with hard water, it reacts with the calcium and magnesium ions of hard water to form an insoluble precipitate called scum. Scum sticks to the cloth to be washed, making cleaning clothes difficult.
Q6. Name the functional groups present in the following compounds
(a ) CH3COCH2CH2CH2CH3
(b ) CH3CH2CH2COOH
(c ) CH3CH2CH2CH2CHO
(d ) CH3CH2OH
Answer:
(a ) A ketone functional group is present in the compound CH3COCH2CH2CH2CH3.
(b ) A carboxylic acid functional group is present in the compound CH3CH2CH2COOH.
(c ) An aldehyde functional group is present in the compound CH3CH2CH2CH2CHO.
(d ) An alcohol functional group is present in the compound CH3CH2OH.
Q7. How is ethene prepared from ethanol? Give the reaction involved in it.
Answer:
Ethanol is heated at 443 k in excess of concentrated sulphuric acid to obtain ethene.
CH3CH2OH + Conc. H2SO4 → CH2 = CH2 + H2O
Q8. Intake of a small quantity of methanol can be lethal. Comment.
Answer:
Intake of a small quantity of Methanol can be lethal as it reacts rapidly with the components of cells. It causes the protoplasm to coagulate. It also affects the optic nerve and causes blindness.
Q9. Gas is evolved when ethanol reacts with sodium. Name the gas evolved and write the balanced chemical equation of the reaction involved.
Answer:
Hydrogen gas is evolved when ethanol reacts with sodium.
2 Na + 2 CH3CH2OH → 2 CH3CH2ONa + H2
Q10. Ethene is formed when ethanol at 443 K is heated with excess concentrated sulphuric acid. What is the role of sulphuric acid in this reaction? Write the balanced chemical equation of this reaction.
Answer:
Concentrated sulphuric acid removes water from ethanol, thereby acting as a dehydrating agent.
CH3CH2OH + Conc H2SO4 → CH2 = CH2 + H2O
Q11. Carbon, the Group (14) element in the Periodic Table, is known to form compounds with many elements. Write an example of a compound formed with
(a ) Chlorine (Group 17 of the periodic table)
(b ) Oxygen (Group 16 of the periodic table)
Answer:
(a ) Carbon tetrachloride (CCl4)
(b ) Carbon dioxide (CO2)
Q12. Crosses or dots in the electron dot structure represent the valence shell electrons.
(a) The atomic number of chlorine is 17. Write its electronic configuration
Answer:
(a ) The electronic configuration of chlorine atom is 2, 8, 7
Q13. Catenation is the ability of an atom to form bonds with other atoms of the same element. Both carbon and silicon exhibit it. Compare the ability of catenation of the two elements. Give reasons.
Answer:
Both carbon and silicon show catenation. But compounds made with silicon are more reactive and less stable. In contrast, bonds formed by carbon are very strong, so organic compounds are more stable than silicon compounds. Thus, we can say that carbon shows better catenation than silicon.
Q14. Unsaturated hydrocarbons contain multiple bonds between the two C-atoms and show addition reactions. Give the test to distinguish ethane from ethene.
Answer:
The bromine water test can be used to distinguish between saturated and unsaturated hydrocarbons. Saturated compounds don’t give an addition reaction. Hence, there won’t be any change in the reaction mixture. In contrast, if an unsaturated hydrocarbon is added to bromine water, its colour will decolourise.
Saturated hydrocarbon + Br₂ → No Reaction (No Colour Change)
Unsaturated hydrocarbon + Br₂ → Reaction will occur (Decolourise)
Q15. Match the reactions given in Column (A) with the names given in column (B).
| Column (A) | Column (B) |
| CH3OH + CH3COOH + H+ → CH3COOCH3 + H2O | Addition reaction |
| CH2 = CH2 + H2 + Ni → H3C – CH3 | Substitution reaction |
| CH4 + Cl2 + Sunlight → CH3Cl + HCl | Neutralisation reaction |
| CH3COOH + NaOH → CH3COONa + H2O | Esterification reaction |
Answer:
| Column (A) | Column (B) |
| CH3OH + CH3COOH + H+ → CH3COOCH3 + H2O | Esterification reaction |
| CH2 = CH2 + H2 + Ni → H3C – CH3 | Addition reaction |
| CH4 + Cl2 + Sunlight → CH3Cl + HCl | Substitution reaction |
| CH3COOH + NaOH → CH3COONa + H2O | Neutralisation reaction |
Q16. Write the structural formulae of all the isomers of hexane.
Answer:
There are five isomers of hexane.
Q17. What is the role of metal or reagents written on arrows in the given chemical reactions?
Answer:
(a ) Ni acts as a catalyst.
(b ) Concentrated H2SO4 acts as a catalyst and a dehydrating agent.
(c ) Alkaline KMnO4 acts as an oxidising agent.
Long Answer Type Questions
Q1. A salt X is formed, and gas is evolved when ethanoic acid reacts with sodium hydrogen carbonate. Name the salt X and the gas evolved. Describe an activity and draw the diagram of the apparatus to prove that the evolved gas is the one you have named. Also, write a chemical equation of the reaction involved.
Answer:
The salt X is sodium ethanoate (CH3COONa), and the evolved gas is carbon dioxide (CO2).
Take a test tube and add ethanoic acid (CH3COOH). Add sodium bicarbonate (NaHCO3) to the acid, close the test tube’s mouth with a cork, and attach a delivery tube.
Take lime water in another test tube and attach it to the delivery tube. The lime water turns milky. This indicates that the evolved gas is carbon dioxide.
Ca(OH)2 + CO2 → CaCO3 + H2O
The milkiness is due to the formation of CaCO3.
Reaction Involved: CH3COOH + NaHCO3 → CH3COONa + H2O + CO2 (g)
Q2. (a ) What are hydrocarbons? Give examples.
(b ) Give the structural differences between saturated and unsaturated hydrocarbons with two examples each.
(c ) What is a functional group? Give examples of four different functional groups.
Answer:
(a ) A hydrocarbon is any of a class of organic compounds made up of carbon and hydrogen. Methane and Ethane are examples of hydrocarbons.
(b )
| S. No. | Saturated hydrocarbon | Unsaturated hydrocarbon |
| 1. | Saturated hydrocarbons contain carbon-carbon single bonds. | Unsaturated hydrocarbons contain at least one carbon-carbon double or triple bond. |
| 2. | They have sp3 hybridised carbon atoms having a general formula CnH2n + 2. | They have sp2 or sp hybridised carbon atoms having a general formula CnH2n or CnH2n – 2. |
(c ) A functional group is the atoms group in a molecule that specifies the chemical behaviour of the molecule. Atoms in a functional group are bonded by the covalent bond.
Q3. Name the reaction which is commonly used in the conversion of vegetable oils to fats. Explain the reaction involved in detail.
Answer:
Vegetable oils generally have long chains of unsaturated carbons, while animal fats have long chains of saturated carbons. An addition reaction is used in the conversion of vegetable oils to fats. It is known as the hydrogenation of oil.
An addition reaction is carried out in the presence of Ni as a catalyst.
Q4. (a ) Write the formula and draw the electron dot structure of carbon tetrachloride.
(b ) What is saponification? Write the reaction involved in this process.
Answer:
(a ) The formula of carbon tetrachloride is CC4.
Electron dot structure of Carbon tetrachloride:
(b ) Saponification is a methodology of manufacturing soap by the hydrolysis of fats or oils with a base like sodium hydroxide.
Reaction: CH3COOC2H5 + NaOH → CH3COONa + C2H5OH
Q5. Esters are sweet-smelling substances and are used in making perfumes. Suggest some activity and reaction in preparing an ester with a well-labelled diagram.
Answer:
Esters are produced by heating carboxylic acids with alcohols in the presence of an acid catalyst. The catalyst that can be used is concentrated sulphuric acid.
CH3COOH + CH3CH2OH + Conc. H2SO4 ⟶ CH3CH2COOCH2CH3 + H2O
Q6. A compound C (molecular formula, C2H4O2) reacts with Na – metal to form a compound R and evolves into a gas which burns with a pop sound. Compound C on treatment with an alcohol A in the presence of an acid forms a sweet-smelling compound S (molecular formula, C3H6O2). On addition of NaOH to C, it also gives R and water. S on treatment with NaOH solution gives back R and A. Identify C, R, A, and S and write down the reactions involved.
Answer:
Here, compound C is ethanoic acid (CH3COOH), compound R is sodium ethanoate (CH3COONa), compound A is ethanol (C2H5OH), and compound S is ethyl ethanoate (CH3COOC2H5).
- Ethanoic acid (CH3COOH) reacts with sodium metal to form sodium ethanoate (CH3COONa).
2 CH3COOH + 2 Na → 2 CH3COONa + H2
- Ethanoic acid (CH3COOH) on treatment with ethanol (C2H5OH) in the presence of an acid forms a sweet-smelling ethyl ethanoate (CH3COOC2H5).
CH3COOH + C2H5OH → CH3COOC2H5 + H2O
- On adding NaOH to ethanoic acid (CH3COOH), it also gives sodium ethanoate (CH3COONa) and water.
CH3COOC2H5 + NaOH → CH3COONa + C2H5OH
Thus, compound C is Ethanoic acid.
Q7. Look at Figure 4.1 and answer the following questions
(a ) What change would you observe in the calcium hydroxide solution taken in tube B?
(b ) Write the reaction involved in test tubes A and B.
(c ) Would you expect the same change if ethanol is given instead of ethanoic acid?
(d ) How can a solution of lime water be prepared in the laboratory?
Answer:
(a ) Calcium hydroxide solution in test tube B will become milky due to the formation of calcium carbonate.
(b ) Reaction in test tube A:
CH3COOH + NaHCO3 → CH3COONa + CO2 + H2O
Reaction in test tube B:
Ca(OH)2 + CO2 → CaCO3 + H2O
(c ) If ethanol is given instead of ethanoic acid, similar changes won’t be observed because ethanol does not react with sodium hydrogen carbonate.
(d ) First, take distilled water in a beaker and mix calcium carbonate powder. After stirring entirely, wait till the mixture settles down. Decant the clear liquid from the beaker. This liquid is lime water.
Q8. How would you bring about the following conversions? Name the process and write the
reaction.
(a) Ethanol to Ethene.
(b) Propanol to Propanoic acid.
Answer:
(a) Ethanol is heated at 443 K in the presence of an excess of conc. Sulphuric acid. This reaction is known as dehydrogenation.
CH3CH2OH + Conc. H2SO4 → CH2 = CH2 + H2O.
(b) Propanol is treated with alkaline potassium permanganate or acidified potassium dichromate to get propanoic acid.
CH3CH2CH2OH + Alkaline KMnO4 / Acidified K2Cr2O7 → CH3CH2COOH
Q9. Draw the possible isomers of the compound with the molecular formula C3H6O and give their electron dot structures.
Answer:
The two possible isomers of the compound with the molecular formula C2H6O are
Electron dot structures of the compound with the molecular formula C2H6O are
Q10. Explain the given reactions with the examples
(a) Hydrogenation reaction
(b) Oxidation reaction
(c) Substitution reaction
(d) Saponification reaction
(e) Combustion reaction
Answer:
(a) Addition of hydrogen to an unsaturated hydrocarbon to get a saturated hydrocarbon is known as a hydrogenation reaction.
CH2 = CH2 + H2 + Ni → CH3 − CH3
(b) When oxygen is added to alcohol to make carboxylic acid, it is known as an oxidation reaction.
CH3CH2CH2OH + Alkaline KMnO4 / Acidified K2Cr2O7 → CH3CH2COOH
(c ) A substitution reaction is a class of chemical reactions in which another atom or group substitute an atom or group of atoms.
CH4 + Cl2 + Sunlight → CH3Cl + HCl
(d) Saponification is a methodology of manufacturing soap by the hydrolysis of fats or oils with a base like sodium hydroxide.
Reaction: CH3COOC2H5 + NaOH → CH3COONa + C2H5OH
(e) A combustion reaction is a chemical reaction in which a compound and an oxidant react to form heat and a new product.
Example: Burning of wood.
Q11. An organic compound A on heating with concentrated H2SO4 forms a compound B which on the addition of one mole of hydrogen in presence of Ni forms a compound C. One mole of compound C on combustion forms two moles of CO2 and 3 moles of H2O. Identify the compounds A, B and C and write the chemical equations of the reactions involved.
Answer:
Compound A is ethanol (CH3CH2OH). When it is heated with concentrated sulphuric acid, we get ethene (CH2 = CH2). Thus, compound B is ethene (CH2 = CH2).
CH3CH2OH + Conc.H2SO4 → CH2 = CH2 + H2O
When ethene (CH2 = CH2) is heated in the presence of nickel, we get ethane (CH3 - CH3).
Thus, compound C is ethane (CH3 - CH3).
CH2 = CH2 + Ni → CH3 - CH3
When 1 mole of ethane (CH3 - CH3) is burnt, we get 2 moles of carbon dioxide (CO2) and 3 moles of water (H2O).
2 CH3 - CH3 + 7 O2 → 4 CO2 + 6 H2O
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