Class 10 Science · Chapter 4

Carbon and its Compounds

442 Class 10 Science questions on Carbon and its Compounds from the NCERT textbook, NCERT Exemplar and CBSE board papers 2017–2026, each with its answer and a step-by-step solution.

CBSE Class 10 Science previous year papers, with answers →

Questions · page 10 of 23

1. Q181 CBSE 2024
   A ​hydrocarbon which contains ​two $\text{C}-\text{C}$ single ​bonds and ​one $\text{C}\equiv \text{C}$ triple ​bond ​is :

   1. (a)Ethyne
   2. (b)Propyne
   3. (c)Butyne
   4. (d)Benzene
   Show answer

   (c) Butyne

   Step-by-step solution →
2. Q182 CBSE 2024
   The number of single and double bonds ​present in ​a ​molecule of ​benzene (${\text{C}}_6{\text{H}}_6$) ​respectively, are :

   1. (a)6 and 6
   2. (b)9 and 3
   3. (c)3 and 9
   4. (d)3 and 3
   Show answer

   (b) 9 and 3

   Step-by-step solution →
3. Q183 CBSE 2024
   Select ​a ​group ​of ​unsaturated ​hydrocarbons from the following ​:

   1. (a)Ethane, propane, butane
   2. (b)Ethyne, butene, cyclohexane
   3. (c)Ethene, propene, butyne
   4. (d)Methane, ethene, propyne
   Show answer

   (c) Ethene, propene, butyne

   Step-by-step solution →
4. Q184 CBSE 2024
   Which one ​of the following ​hydrocarbons ​is different from ​the ​others ​?

   1. (a)${\text{C}}_4{\text{H}}_{10}$
   2. (b)${\text{C}}_7{\text{H}}_{14}$
   3. (c)${\text{C}}_5{\text{H}}_{12}$
   4. (d)${\text{C}}_2{\text{H}}_6$
   Show answer

   (b) ${\text{C}}_7{\text{H}}_{14}$

   Step-by-step solution →
5. Q185 CBSE 2024
   Select ​saponification ​reaction from ​the ​following :

   1. (a)${\text{C}}_4{\text{H}}_9\text{OH}\underset{{\text{KMnO}}_4}{\overset{\text{Alkaline}}{\to }}{\text{C}}_3{\text{H}}_7\text{COOH}$
   2. (b)$2{\text{C}}_2{\text{H}}_5\text{OH}+2\text{Na}⟶2{\text{C}}_2{\text{H}}_5\text{COONa}+{\text{H}}_2$
   3. (c)${\text{CH}}_3{\text{COOC}}_2{\text{H}}_5+\text{NaOH}⟶{\text{CH}}_3\text{COONa}+{\text{C}}_2{\text{H}}_5\text{OH}$
   4. (d)${\text{CH}}_3\text{COONa}+\text{NaOH}⟶{\text{CH}}_4+{\text{Na}}_2{\text{CO}}_3$
   Show answer

   (c) ${\text{CH}}_3{\text{COOC}}_2{\text{H}}_5+\text{NaOH}⟶{\text{CH}}_3\text{COONa}+{\text{C}}_2{\text{H}}_5\text{OH}$

   Step-by-step solution →
6. Q186 CBSE 2024
   Identify ​a group of ​the unsaturated ​hydrocarbons from ​the following ​:

   1. (a)Propane, Ethene, Butyne
   2. (b)Ethene, Propane, Hexane
   3. (c)Cyclohexane, Methane, Ethane
   4. (d)Butyne, Ethene, Propyne
   Show answer

   (d) Butyne, Ethene, Propyne

   Step-by-step solution →
7. Q187 CBSE 2024
   In ​the structure ​of cyclohexane $({\text{C}}_6{\text{H}}_{12})$ ​there are :

   1. (a)Six single bonds, four double bonds and two triple bonds
   2. (b)Six single bonds, two double bonds and one triple bond
   3. (c)Eight single bonds and five double bonds
   4. (d)Eighteen single bonds only
   Show answer

   (d) Eighteen single bonds only

   Step-by-step solution →
8. Q188 CBSE 2024
   Consider the following statements about ​homologous series of carbon compounds :

   1. (a)All succeeding members ​differ by $-{\text{CH}}_2$ unit.
   2. (b)Melting point and boiling point increases with increasing molecular mass.
   3. (c)The difference in molecular masses between two successive members ​is 16 ​u.
   4. (d)${\text{C}}_2{\text{H}}_2$ and ${\text{C}}_3{\text{H}}_4$ ​are NOT the successive ​members of ​alkyne series. The ​correct statements are –

   1. (a)(a) and (b)
   2. (b)(b) and (c)
   3. (c)(a) and (c)
   4. (d)(c) and (d)
   Show answer

   (a) (a) and (b)

   Step-by-step solution →
9. Q189 CBSE 2024
   One ​mole of a hydrocarbon, on combustion in air, produces ​two moles of ${\text{CO}}_2$, two moles of ${\text{H}}_2\text{O}$ and ​a large amount ​of heat. This ​hydrocarbon ​is :

   1. (a)ethyne
   2. (b)ethene
   3. (c)ethane
   4. (d)methane
   Show answer

   (b) ethene

   Step-by-step solution →
10. Q190 CBSE 2024
    Two statements are given ​— one labelled as Assertion ​(A) and the other labelled ​as Reason (R). Select the ​correct ​answer to ​this ​question from the codes (a), (b), (c) and ​(d) as given below.

    Assertion (A): Some vegetable oils are healthy.

    Reason (R): Vegetable oils generally have long unsaturated carbon chains.

    1. (a)Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
    2. (b)Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
    3. (c)Assertion (A) is true, but Reason (R) is false.
    4. (d)Assertion (A) is false, but Reason (R) is true.
    Show answer

    (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).

    Step-by-step solution →
11. Q191 CBSE 2024
    Two statements are given — one labelled as ​Assertion ​(A) and the other labelled as Reason (R). Select the correct ​answer to this question ​from the codes (a), ​(b), (c) and ​(d) as given ​below.

    Assertion (A): Soaps do not form lather (foam) with hard water.

    Reason (R): Hard water has calcium and magnesium salts dissolved in it which on reacting with soap form scum.

    1. (a)Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).
    2. (b)Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of Assertion (A).
    3. (c)Assertion (A) is true, but Reason (R) is false.
    4. (d)Assertion (A) is false, but Reason (R) is true.
    Show answer

    (a) Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of Assertion (A).

    Step-by-step solution →
12. Q192 CBSE 2024
    Distinguish between ​a ​saturated and an unsaturated hydrocarbon by flame ​test. List the products ​of combustion ​reaction ​of ​a saturated hydrocarbon.
    Show answer

    Saturated hydrocarbons burn with a clean blue flame, unsaturated ones with a sooty yellow flame; combustion gives carbon dioxide and water.

    Flame test: a saturated hydrocarbon burns in air with a clean, blue flame without smoke, whereas an unsaturated hydrocarbon burns with a yellow flame giving lots of black smoke (soot). Products of combustion of a saturated hydrocarbon: carbon dioxide and water, with the release of heat and light — e.g. ${\text{CH}}_4+2{\text{O}}_2\to {\text{CO}}_2+2{\text{H}}_2\text{O}+\text{heat and light}$.

    Step-by-step solution →
13. Q193 CBSE 2024
    A spatula ​full of sodium carbonate is taken ​in a test tube ​and 2 mL of dilute ​ethanoic acid ​is added ​to it.

    1. (a)Write a chemical equation for the reaction.
    2. (b)Suggest a method of testing the ​gas liberated in ​the reaction.
    Show answer

    Ethanoic acid and sodium carbonate give sodium ethanoate, water and carbon dioxide; the gas turns lime water milky.

    (a) $2{\text{CH}}_3\text{COOH}+{\text{Na}}_2{\text{CO}}_3\to 2{\text{CH}}_3\text{COONa}+{\text{H}}_2\text{O}+{\text{CO}}_2$ (sodium ethanoate, water and carbon dioxide; brisk effervescence is seen). (b) Pass the gas liberated through freshly prepared lime water with a delivery tube dipping into it: the lime water turns milky because insoluble calcium carbonate forms, ${\text{Ca(OH)}}_2+{\text{CO}}_2\to {\text{CaCO}}_3+{\text{H}}_2\text{O}$, which shows that the gas is carbon dioxide.

    Step-by-step solution →
14. Q194 CBSE 2024
    When a ​soap is ​dissolved in water, the ​soap molecules ​form structures. What are these structures called ​? Draw a labelled diagram of these structures.
    Show answer

    The structures are micelles: soap molecules cluster with hydrocarbon tails inwards and ionic ends facing the water.

    The structures are called micelles. In a micelle, soap molecules form a spherical cluster with their hydrocarbon (hydrophobic) tails pointing inwards, towards the centre where oily dirt collects, and their ionic $-{\text{COO}}^{-}{\text{Na}}^{+}$ (hydrophilic) ends on the outside facing the water, as shown in the labelled diagram.

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15. Q195 CBSE 2024
    The ​melting and boiling points of ​carbon compounds are ​generally low and they are largely ​non-conductors of electricity. State two conclusions ​based on ​these two properties.
    Show answer

    Low melting and boiling points show weak forces between molecules; non-conduction shows covalent bonding with no ions.

    Conclusion 1: the low melting and boiling points show that the forces of attraction between the molecules of carbon compounds are not very strong, so little heat is needed to separate the molecules. Conclusion 2: being largely non-conductors of electricity shows that the bonding in carbon compounds does not give rise to any ions; their atoms are held together by covalent bonds, formed by the sharing of electrons.

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16. Q196 CBSE 2024
    Identify ​the ​functional ​group present ​in the following ​compounds and also ​name ​them :

    Show answer

    (a) Carboxylic acid group $-\text{COOH}$ in ethanoic acid; (b) aldehyde group $-\text{CHO}$ in methanal.

    (a) The functional group is the carboxylic acid group, $-\text{COOH}$, and the compound is ethanoic acid (acetic acid), ${\text{CH}}_3\text{COOH}$. (b) The functional group is the aldehyde group, $-\text{CHO}$, and the compound is methanal (formaldehyde), $\text{HCHO}$.

    Step-by-step solution →
17. Q197 CBSE 2024
    Write the formula and the molecular mass of ​the third homologue ​of alcohols. State how the ​boiling point ​of an alcohol changes as ​one ​moves from lower to higher ​homologues.
    Show answer

    Propanol, ${\text{C}}_3{\text{H}}_7\text{OH}$, has molecular mass 60 u; boiling point increases from lower to higher homologues.

    The third homologue of alcohols is propanol, ${\text{C}}_3{\text{H}}_7\text{OH}$ (${\text{CH}}_3-{\text{CH}}_2-{\text{CH}}_2-\text{OH}$), with molecular mass $3\times 12+8\times 1+16=60$ u. The boiling point of an alcohol increases as one moves from lower to higher homologues, because the molecular mass increases.

    Step-by-step solution →
18. Q198 CBSE 2024
    Why is the conversion of ethanol to ethanoic ​acid an oxidation reaction ​? Name the oxidising ​agent used in this ​conversion. ​Write chemical equation for ​this oxidation ​reaction. How is this reaction different from the reaction in which ethanol burns in the presence of oxygen ?
    Show answer

    Ethanol gains oxygen and loses hydrogen, so it is oxidised to ethanoic acid by alkaline ${\text{KMnO}}_4$; unlike burning, it is a controlled partial oxidation.

    It is an oxidation because oxygen is added to ethanol and hydrogen is removed from it: ${\text{CH}}_3{\text{CH}}_2\text{OH}$ (${\text{C}}_2{\text{H}}_6\text{O}$) gains one oxygen atom and loses two hydrogen atoms to become ${\text{CH}}_3\text{COOH}$ (${\text{C}}_2{\text{H}}_4{\text{O}}_2$). Oxidising agent: alkaline potassium permanganate (or acidified potassium dichromate). Equation: ${\text{CH}}_3{\text{CH}}_2\text{OH}\stackrel{{\text{alkaline KMnO}}_4+\text{heat}}{\to }{\text{CH}}_3\text{COOH}$, i.e. ${\text{CH}}_3{\text{CH}}_2\text{OH}+2[\text{O}]\to {\text{CH}}_3\text{COOH}+{\text{H}}_2\text{O}$. Difference: this is a controlled (partial) oxidation by an oxidising agent, without burning — the two-carbon chain is kept and ethanoic acid is formed. When ethanol burns in oxygen it undergoes complete oxidation (combustion) with a flame, forming only carbon dioxide and water with the release of heat and light: ${\text{C}}_2{\text{H}}_5\text{OH}+3{\text{O}}_2\to 2{\text{CO}}_2+3{\text{H}}_2\text{O}$.

    Step-by-step solution →
19. Q199 CBSE 2024
    Write ​chemical equations for the following reactions, ​giving the conditions for ​the reaction in each case :

    1. (a)Reaction ​of ​ethanol with ethanoic acid
    2. (b)Reaction of an ester with a base ​($\text{NaOH}$)
    3. (c)Formation of ethene from ethanol
    Show answer

    Esterification needs warm conc. ${\text{H}}_2{\text{SO}}_4$, saponification needs heating with NaOH, and ethanol gives ethene at 443 K with conc. ${\text{H}}_2{\text{SO}}_4$.

    (a) ${\text{CH}}_3\text{COOH}+{\text{CH}}_3{\text{CH}}_2\text{OH}\underset{\text{warm}}{\overset{{\text{conc. H}}_2{\text{SO}}_4}{\to }}{\text{CH}}_3{\text{COOCH}}_2{\text{CH}}_3+{\text{H}}_2\text{O}$. Condition: a few drops of concentrated sulphuric acid as catalyst, warming. (b) ${\text{CH}}_3{\text{COOC}}_2{\text{H}}_5+\text{NaOH}\stackrel{\text{heat}}{\to }{\text{CH}}_3\text{COONa}+{\text{C}}_2{\text{H}}_5\text{OH}$. Condition: heating with sodium hydroxide solution (saponification). (c) ${\text{CH}}_3{\text{CH}}_2\text{OH}\underset{443\text{K}}{\overset{{\text{hot conc. H}}_2{\text{SO}}_4}{\to }}{\text{CH}}_2={\text{CH}}_2+{\text{H}}_2\text{O}$. Condition: heating at $443$ K with excess concentrated sulphuric acid, which acts as a dehydrating agent.

    Step-by-step solution →
20. Q200 CBSE 2024
    Consider the following organic compounds : ${\text{C}}_2{\text{H}}_5\text{CHO}$, ${\text{CH}}_3\text{COOH}$, ${\text{C}}_2{\text{H}}_5\text{OH}$, ${\text{CH}}_3{\text{COCH}}_3$

    1. (a)Which one of these ​compounds when heated at 443 K in excess conc. ${\text{H}}_2{\text{SO}}_4$ forms ethene as its ​major product ? State the role of conc. ${\text{H}}_2{\text{SO}}_4$ in the reaction. ​Also, write the chemical ​equation for the chemical reaction involved.
    2. (b)Give chemical equation for the chemical reaction when ${\text{CH}}_3\text{COOH}$ and ${\text{C}}_2{\text{H}}_5\text{OH}$ ​react ​in the presence of conc. ${\text{H}}_2{\text{SO}}_4$.
    Show answer

    Ethanol dehydrates to ethene with hot conc. ${\text{H}}_2{\text{SO}}_4$, a dehydrating agent; ethanoic acid and ethanol form the ester ethyl ethanoate.

    (a) Ethanol, ${\text{C}}_2{\text{H}}_5\text{OH}$. Conc. ${\text{H}}_2{\text{SO}}_4$ acts as a dehydrating agent: it removes a molecule of water from each molecule of ethanol. ${\text{CH}}_3{\text{CH}}_2\text{OH}\underset{\text{443 K}}{\overset{{\text{hot conc. H}}_2{\text{SO}}_4}{\to }}{\text{CH}}_2={\text{CH}}_2+{\text{H}}_2\text{O}$ (b) Ethanoic acid and ethanol react in the presence of conc. ${\text{H}}_2{\text{SO}}_4$ (an acid catalyst) to give the sweet-smelling ester ethyl ethanoate and water (esterification): ${\text{CH}}_3\text{COOH}+{\text{C}}_2{\text{H}}_5\text{OH}\stackrel{{\text{conc. H}}_2{\text{SO}}_4}{\to }{\text{CH}}_3{\text{COOC}}_2{\text{H}}_5+{\text{H}}_2\text{O}$

    Step-by-step solution →