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NCERT Exemplar Solution for CBSE Class 10 Science Chapter 4: Carbon and Its Compounds (Part-I)

May 15, 2017 12:05 IST

    Class 10 Science NCERT Exemplar Problems, Class 9 NCERT Exemplar Problems and SolutionsHere you get the CBSE Class 10 Science chapter 4, Carbon and Its Compounds: NCERT Exemplar Solution (Part-I). This part of the chapter includes solutions for Question No.1 to 29 from the NCERT Exemplar Problems for Class 10 Science Chapter: Carbon and Its Compounds. These questions include only the Multiple Choice Questions (MCQs) framed from various important topics of the chapter.

    CBSE Class 10 Science Syllabus 2017-2018

    NCERT Exemplar problems are a very good resource for preparing the critical questions like Higher Order Thinking Skill (HOTS) questions. All these questions are very important to prepare for CBSE Class 10 Science Board Examination 2017-2018 as well as other competitive exams.

    Find below the NCERT Exemplar problems and their solutions for Class 10 Science Chapter, Carbon and Its Compounds:

    Multiple Choice Questions (MCQs)

    Question. 1 Carbon exists in the atmosphere in the form of

    (a) Only carbon monoxide

    (b) Carbon monoxide in traces and carbon dioxide

    (c) Only carbon dioxide

    (d) Coal

    Answer. (c)

    Explanation: Carbon exists only in the form of carbon dioxide gas (CO2) in air.

    Question. 2 Which of the following statements are usually correct for carbon compounds? These

    (i) Are good conductors of electricity.

    (ii) Are poor conductors of electricity.

    (iii) Have strong forces of attraction between their molecules.

    (iv) Do not have strong forces of attraction between their molecules.

                (a) (i) and (iii)

                (b) (ii) and (iii)

                (c) (i) and (iv)

                (d) (ii) and (iv)

    Answer. (d)

    Explanation: Carbon having four valence electrons forms only covalent compounds which exhibit less intermolecular attractions  and do not have any fre electrons to carry electric current. Therefore, these are poor conductors of electricity.

    Question. 3 A molecule of ammonia (NH3) has

    (a) Only single bonds

    (b) Only double bonds

    (c) Only triple bonds

    (d) Two double bonds and one single bond

    Answer. (a)

    Explanation: Ammonia is a covalent molecule in which center nitrogen atom is bonded with three hydrogen atoms through single covalent bond.

    Question. 4 Buckminsterfullerene is an allotropic form of

    (a) Phosphorus

    (b) Sulphur

    (c) Carbon

    (d) Tin

    Answer. (c)

    Explanation: Buckminsterfullerene is an allotrope of carbon with 60 carbon atoms which are joined together in a spherical shape.

    Question. 5 Which of the following are correct structural isomers of C4H10?          

    structural isomers of C4H10

                (a) (i) and (iii)

                (b) (ii) and (iv)

                (c) (i) and (ii)

                (d) (iii) and (iv)

    Answer. (a)

    Explanation: Structural isomers have same molecular formula but different parent chain of carbon atoms in the molecule.

    Question. 6 In the following reaction, alkaline KMnO4 acts as:

    alkaline KMnO4 as oxidising agent

    (a) Reducing agent

    (b) Oxidising agent

    (c) Catalyst

    (d) Dehydrating agent

    Answer. (b)

    Explanation: KMnO4 acts as oxidising agent as it oxidized CH3CH2OH to CH3COOH by addition of oxygen atom.

    Question. 7 Oils on treating with hydrogen in the presence of palladium or nickel catalyst form fats. This is an example of

    (a) Addition reaction

    (b) Substitution reaction

    (c) Displacement reaction

    (d) Oxidation reaction

    Answer. (a)

    Explanation: It is hydrogenation reaction means addition of hydrogen to double bonds of unsaturated compounds found in oil.

    hydrogenation of oils

    Question. 8 In which of the following compounds -OH is the functional group?

    (a) Butanone

    (b) Butanol

    (c) Butanoic

    (d) Butanal

    Answer. (b)  

    Explanation: Compounds with –OH functional group are ended with suffix –ol.

    C4H9 ─ OH or CH3 ─ CH2 ─ CH2 ─ CH2 ─ OH

    Question. 9 The soap molecule has a

    (a) Hydrophilic head and a hydrophobic tail

    (b) Hydrophobic head and a hydrophilic tail

    (c) Hydrophobic head and a hydrophobic tail

    (d) Hydrophilic head and a hydrophilic tail

    Answer. (a)

    Explanation: A soap molecule contains a long hydrocarbon part and a small ionic part of -COONa group. Hydrocarbon chain is hydrophobic or water repelling whereas ionic head is hydrophilic or water attracting group.

     structure of soap molecule

    Question. 10 Which of the following is the correct representation of electron dot structure of nitrogen?

    electron dot structure of nitrogen

    Answer. (d)

    Explanation: Nitrogen molecule is a covalent molecule in which two nitrogen atoms are bonded through triple covalent bond with one lone pair of electrons over each nitrogen atom.

    Question. 11 Structural formula of ethyne is

    structural formila of ethyne

    Answer. (a)

    Explanation: General formula for alkyne is CnH2n−2. There must be at least one triple bond between carbon atoms. With two carbon atom, the possible structure would be H ─ C ≡ C ─ H.

    Question. 12 Identify the unsaturated compounds from the following.

    (i) Propane

    (ii) Propene

    (iii) Propyne

    (iv) Chloropropane

                (a) (i) and (ii)

                (b) (ii) and (iv)

                (c) (iii) and (iv)

                (d) (ii) and (iii)

    Answer. (d)

    Explanation: Alkene and alkyne are unsaturated hydrocarbon as they have double and triple covalent bonds between carbon atoms.

    Question. 13 Chlorine reacts with saturated hydrocarbons at room temperature in the

    (a) absence of sunlight

    (b) presence of sunlight

    (c) presence of water

    (d) presence of hydrochloric acid

    Answer. (b)

    Explanation: Chlorine shows photochemical substitution reactions with saturated hydrocarbons that occurs in the presence of light.    

    NCERT Solutions for CBSE Class 10 Science

    Question. 14 In the soap micelles

    (a) The ionic end of soap is on the surface of the cluster while the carbon chain is in the interior of the cluster

    (b) Ionic end of soap is in the interior of the cluster and the carbon chain is out of the cluster

    (c) Both ionic end and carbon chain are in the interior of the cluster

    (d) Both ionic end and carbon chain are on the exterior of the cluster

    Answer. (a)

    Explanation: A micelle is a spherical aggregation of soap molecules in water in which hydrocarbon ends are directed towards the centre and ionic ends are directed outwards.

    Question. 15 Pentane has the molecular formula C5H12. It has

    (a) 5 covalent bonds

    (b) 12 covalent bonds

    (c) 16 covalent bonds

    (d) 17 covalent bonds

    Answer. (c)

    Explanation: Pentane contains four C-C bonds and twelve C-H covalent bonds.

    structural formula of pentane

    Question. 16 Structural formula of benzene is:

    structural formula of benzene

    Answer. (c)

    Explanation: Benzene is simplest aromatic compound with six carbon atoms and six H atoms. There are three alternate pi bonds in ring of carbon atoms.

    Question. 17 Ethanol reacts with sodium and forms two products. These are

    (a) Sodium ethanoate and hydrogen

    (b) Sodium ethanoate and oxygen

    (c) Sodium ethoxide and hydrogen

    (d) Sodium ethoxide and oxygen

    Answer. (c)

    Explanation: Ethanol (C2H5OH) reacts with sodium to form sodium ethoxide (C2H5ONa) along with liberation of hydrogen gas.

    2C2H5OH  +  2Na  →  2C2H5ONa   +   H2 ↑                

    Question. 18 The correct structural formula of butanoic acid is: structural formula of butanoic acid

    Answer. (d)

    Explanation:  Butanoic acid is a carboxylic acid with four carbon atom and one –COOH group at terminal.

    Question. 19 Vinegar is a solution of:

    (a) 50% - 60% acetic acid in alcohol

    (b) 5% - 8% acetic acid in alcohol

    (c) 5% - 8% acetic acid in water

    (d) 50%- 60% acetic acid in water

    Answer. (c)

    Explanation:  Vinegar is a 5%-8% aqueous solution of acetic acid.

    Question. 20 Mineral acids are stronger acids than carboxylic acids because

    (i) Mineral acids are completely ionised.

    (ii) Carboxylic acids are completely ionised.

    (iii) Mineral acids are partially ionised.

    (iv) Carboxylic acids are partially ionised.

                (a) (i) and (iv)

                (b) (ii) and (iii)

                (c) (i) and (ii)

                (d) (iii) and (iv)

    Ans. (a)

    Explanation: Mineral acids like nitric acid, sulphuric acid are stronger than carboxylic acid as they can ionize 100% in their solution.

    Question. 21 Carbon forms four covalent bonds by sharing its four valence electrons with four univalent atoms, e.g. hydrogen. After the formation of four bonds, carbon attains the electronic configuration of

    (a) Helium

    (b) Neon

    (c) Argon

    (d) Krypton

    Answer. (b)

    Explanation:  Electronic configuration of carbon is 2, 4 hence it contains 4 valence electrons and after formation of 4 covalent bonds, it will get 4 more electrons through them so total would be 10 electrons that is atomic number for Neon gas.

    Question. 22 The correct electron dot structure of a water molecule is

    electron dot structure of water molecule

    Answer. (c)

    Explanation: In water molecule, center oxygen atom contains two lone pairs of electrons and form two single covalent bonds with two hydrogen atoms.

    Question. 23 Which of the following is not a straight chain hydrocarbon?

    straight chain hydrocarbon

    Answer. (d)

    Explanation: A branched chain hydrocarbon must contain some side chains which are bonded with parent carbon chain.

    Question. 24 Which among the following are unsaturated hydrocarbons?

    formula of unsaturated hydrocarbon

                (a) (i) and (iii)

                (b) (ii) and (iii)

                (c) (ii) and (iv)

                (d) (iii) and (iv)

    Answer. (c)

    Explanation: Unsaturated hydrocarbons have multiple covalent bonds (double or triple bond) like alkene and alkyne.

    Question. 25 Which of the following does not belong to the same homologous series?

    (a) CH4

    (b) C2H6

    (c) C3H8

    (d) C4H8

    Answer. (d)

    Explanation:  Successive members of same homologous series are differ by - CH2 unit. CH4, C2H6, C3H8 belong to same series that is of alkane and differ by ─ CH2 unit but C4H8 does not belong to this.

    Question. 26 The name of the compound, CH3 ─ CH2 ─ CHO is:

    (a) Propanal

    (b) Propanone

    (c) Ethanol

    (d) Ethanal

    Answer. (a)

    Explanation:  Compound contains three carbon atoms so prop- would be root word and – CHO functional group so suffix will be –al. Hence name would be propane + al = propanal.

    Question. 27 The heteroatoms present in CH3 ─ CH2 ─ O ─ CH2 ─ CH2Cl are:

    (i) Oxygen

    (ii) Carbon

    (iii) Hydrogen

    (iv) Chlorine

                (a) (i) and (ii)

                (b) (ii) and (iii)

                (c) (iii) and (iv)

                (d) (i) and (iv)

    Answer. (d)

    Explanation:  Atoms other than C and H in organic compound are called as heteroatoms.

    Question. 28 Which of the following represents saponification reaction?

    representation of saponification

    Answer. (d)

    Explanation:  Saponification reaction is reaction of ester with base like NaOH to form the parent alcohol and sodium salt of carboxylic acid.

    Question. 29 The first member of alkyne homologous series is:

    (a) Ethyne

    (b) Ethene

    (C) Propyne

    (d) Methane

    Answer. (a)

    Explanation: Alkyne is an organic compound with triple covalent bond between two carbon atoms therefore first member of homologous series must have atleast two carbon atoms with one triple bond that is ethyne (CH ≡ CH).

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