{"id":8801,"date":"2019-11-26T17:49:21","date_gmt":"2019-11-26T12:19:21","guid":{"rendered":"https:\/\/kseebsolutions.guru\/?p=8801"},"modified":"2021-07-02T15:44:54","modified_gmt":"2021-07-02T10:14:54","slug":"1st-puc-chemistry-question-bank-chapter-13","status":"publish","type":"post","link":"https:\/\/kseebsolutions.guru\/1st-puc-chemistry-question-bank-chapter-13\/","title":{"rendered":"1st PUC Chemistry Question Bank Chapter 13 Hydrocarbons"},"content":{"rendered":"

You can Download Chapter 13 Hydrocarbons Questions and Answers, Notes, 1st PUC Chemistry Question Bank with Answers<\/a> Karnataka State Board Solutions help you to revise complete Syllabus and score more marks in your examinations.<\/p>\n

Karnataka 1st PUC Chemistry Question Bank Chapter 13 Hydrocarbons<\/h2>\n

1st PUC Chemistry Hydrocarbons One Mark Questions and Answers<\/h3>\n

Question 1.
\nWhat are hydrocarbons ?
\nAnswer:
\nOrganic compounds containing only carbon and hydrogen are called hydrocarbons.<\/p>\n

Question 2.
\nWhat are alkanes ?
\nAnswer:
\nAlkanes are saturated aliphatic hydrocarbons containing carbon to carbon single bonds.<\/p>\n

Question 3.
\nGive the general formula of alkanes.
\nAnswer:
\nThe general formula of alkanes is Cn<\/sub>H2n+2<\/sub><\/p>\n

Question 4.
\nWhat are saturated hydrocarbons ?
\nAnswer:
\nThe hydrocarbons containing only carbon – carbon single bonds saturated hydrocarbons.<\/p>\n

Question 5.
\nWhat is the order of reactivity of halogens towards alkanes.
\nAnswer:
\nThe reactivity of halogens towards alkanes varies as Flourine > Chlorine > Bromine > Iodine i.e., F > Cl > Br > I.<\/p>\n

\"KSEEB<\/p>\n

Question 6.
\nWhy alkanes are called parafins ?
\nAnswer:
\nBecause of low reactivity.<\/p>\n

Question 7.
\nWhat is the nature ofC-C bond in alkanes?
\nAnswer:
\nThese are sigma (\u03c3) bonds.<\/p>\n

Question 8.
\nWhat type of structural isomerism is shown by alkanes?
\nAnswer:
\nChain Isomerism.<\/p>\n

Question 9.
\nWhat is Photochemical reaction ?
\nAnswer:
\nReaction carried in the presence of light.<\/p>\n

Question 10.
\nWhich class of organic compounds are potential carcinogen?
\nAnswer:
\nPolynuclear aromatic hydrocarbons.<\/p>\n

Question 11.
\nWhat is huckel Rule ?
\nAnswer:
\nIt states that a compound is said to be aromatic. If it has (4n +2) p electrons which are de-localised where n = 0,1, 2, 3, ………<\/p>\n

Question 12.
\nName the scientist who first isolated benzene.
\nAnswer:
\nFaraday isolated benzene in 1825.<\/p>\n

Question 14.
\nWhat is decarboxylation ?
\nAnswer:
\nThe process of removing carbon dioxide from sodium salts of acid with the help of soda lime.<\/p>\n

Question 15.
\nWhat is electrophilic subsitution reaction ?
\nAnswer:
\nThose reaction in which weaker electrophile is replaced by stronger electrophile are called electrophilic substitution reaction.<\/p>\n

Question 16.
\nWhy is addition reaction of bromine to benzene difficult?
\nAnswer:
\nDue to delocalisation of \u03c0 electrons. It does not have pure double bond.<\/p>\n

Question 17.
\nWhat are arenas? Give general formula of Monocyclic arenas.
\nAnswer:
\nArenes are aromatic hydrocarbons. General formula of arenas is Cn<\/sub>H2n-6<\/sub><\/p>\n

Question 18.
\nWhat are unsaturated hydrocarbons?
\nAnswer:
\nThe hydrocarbons which contain atleast one carbon to carbon double bond or triple bond are called unsaturated hydrocarbons.<\/p>\n

Question 19.
\nWhat type of isomerism is shown by alkenes ?
\nAnswer:
\nChain isomerism.<\/p>\n

Question 20.
\nWhat are alkenes ?
\nAnswer:
\nAlkenes are unsaturated aliphatic hydrocarbons containing one carbon to carbon double bond.<\/p>\n

\"KSEEB<\/p>\n

Question 21.
\nGive the general formula of alkenes.
\nAnswer:
\nThe general formula of alkenes is Cn<\/sub>H2n<\/sub>.<\/p>\n

Question 21.
\nWhy are alkenes and alkenes called unsaturated hydrocarbons?
\nAnswer:
\nDue to presence of C = C & C \u2261 C bonds respectively.<\/p>\n

Question 22.
\nWhat is the state of hybridisation of carbon atoms in alkenes ?
\nAnswer:
\nSp2<\/sup><\/p>\n

Question 23.
\nA compound decolourise yellow colour of bromine. What does it show ?
\nAnswer:
\nIt is unsaturated in nature.<\/p>\n

Question 24.
\nWhat is Lindlar’s catalyst ?
\nAnswer:
\nPalladium supported over calcium carbonate and deactivated with quinoline is called Lindlar’s Catalyst.<\/p>\n

Question 25.
\nName the hydrocarbon which contains acidic hydrogen.
\nAnswer:
\nEthylene (HC \u2261 CH).<\/p>\n

Question 26.
\nGive one hydrocarbon which delcolourises alk KMnO4<\/sub>.
\nAnswer:
\nEthene (CH2<\/sub> = CH2<\/sub>)<\/p>\n

Question 27.
\nName the reagent which brings about dehydrohalogination.
\nAnswer:
\nAlcoholic potash.<\/p>\n

Question 28.
\nWhat is the major product formed when propene reacts with hydrogen bromide ?
\nAnswer:
\n2 – bromopropane.<\/p>\n

Question 29.
\nName the product formed when HBr reacts with 2 – methyl propene.
\nAnswer:
\n\"1st<\/p>\n

Question 30.
\nWhat are alkynes?
\nAnswer:
\nAlkynes are unsaturated aliphatic hydrocarbons containing one carbon to carbon triple bond.<\/p>\n

Question 31.
\nGive the general formula of alkynes.
\nAnswer:
\nThe general formula of alkynes is Cn<\/sub>H2n-2<\/sub><\/p>\n

Question 32.
\nWhat is the hybridisation of carbon atoms in acetylene ?
\nAnswer:
\nsp<\/p>\n

Question 33.
\nWhat is a vicinal dihalide ?
\nAnswer:
\nA compound with halogen atoms on adjacent carbon atom.<\/p>\n

Question 34. Give the example of vicinal dihalide.
\nAnswer:
\n\"1st<\/p>\n

Question 35.
\nGive an example of geminal dihalide.
\nAnswer:
\nCH3<\/sub> – CHCl2<\/sub> (1,1 – dichlorethane)<\/p>\n

\"KSEEB<\/p>\n

Question 36.
\nGive an example of alkyne.
\nAnswer:
\nAcetylene CH \u2261 CH<\/p>\n

Question 37.
\nWhy are alkenes called olefins ?
\nAnswer:
\nBecause they are oily forming compounds i.e., most of the oils are unsaturated.<\/p>\n

Question 38.
\nGive an addition reaction of alkynes.
\nAnswer:
\nCH \u2261 CH + HBr \u2192 CH2<\/sub> \u2261 CH – Br (Vinyl Bromide)<\/p>\n

Question 39.
\nGive the resonance structures of benzene.
\nAnswer:
\n\"1st<\/p>\n

Question 40.
\nName the electrophiles in the following reactions<\/p>\n

    \n
  1. Chlorination<\/li>\n
  2. Nitration<\/li>\n
  3. Sulphonation<\/li>\n
  4. Friedel Craft’s methylation<\/li>\n<\/ol>\n

    Answer:<\/p>\n

      \n
    1. Chlorination – Cl+<\/sup><\/li>\n
    2. Nitration – \\(\\mathrm{NO}_{2}^{+}\\)<\/li>\n
    3. Sulphonation – SO3<\/sub> .<\/li>\n
    4. Friedel Crafts methylation – \\(\\mathrm{CH}_{3}^{+}\\)<\/li>\n<\/ol>\n

      Question 41.
      \nWrite the Geometrical isomers of CHBr = CHBr
      \nAnswer:
      \n\"1st<\/p>\n

      Question 42.
      \nWhich catalyst is most effective even in the polymerization of ethane to polythene ?
      \nAnswer:
      \nZiegler – Nata Catalyst<\/p>\n

      Question 43.
      \nWhat is the compostion of Zeigler Natta Catalyst?
      \nAnswer:
      \nTriethylaluminium and titanium tetracholride inert solvent.<\/p>\n

      Question 44.
      \nName one Carcinogenic compound.
      \nAnswer:
      \nAnthracene of Benzanthracene.<\/p>\n

      Question 45.
      \nWhat is the number of a and n bonds in N \u2261 C-CH = CH- C \u2261 N?
      \nAnswer:
      \nThere are 7 \u03c3 bonds and 5 \u03c0 bonds.<\/p>\n

      Question 46.
      \nName the compound formed when heptane is subjected to aromatisation.
      \nAnswer:
      \nToulene.<\/p>\n

      Question 47.
      \nWhat is the cause of Geometrical Isomerism ?
      \nAnswer:
      \nThe restricted rotation around carbon to carbon double bond<\/p>\n

      Question 48.
      \nWhat is cracking of hydrocarbon ?
      \nAnswer:
      \nCracking is a process of breaking higher hydrocarbons by heating.<\/p>\n

      Question 49.
      \nWhat is the trade name of Benzene Hexacarbon ?
      \nAnswer:
      \nGammaxane.<\/p>\n

      \"KSEEB<\/p>\n

      1st PUC Chemistry Hydrocarbons Two Marks Questions and Answers<\/h3>\n

      Question 1.
      \nWhat is the action of ethane with bromine in carbon tetra chloride?
      \nAnswer:
      \nEthene reacts with bromine in carbon tetrachloride to give 1, 2 – dibromethane. Orange colour of bromine is discharged.
      \n\"1st<\/p>\n

      Question 2.
      \nWhat is the action of hydrogen halide on alkene?
      \nAnswer:
      \nAlkene reacts with hydrogen halide to form alkyl halide. The addition is governed by Markownikoff’s rule.
      \n\"1st<\/p>\n

      Question 3.
      \nHow do you obtain an alkene from alkyne ?
      \nAnswer:
      \nAlkynes react with hydrogen in the presence of (Palladium supported over calcium carbonate and deactivated with quinoline) Lindlar’s catalyst, to give alkene.
      \n\"1st<\/p>\n

      Question 4.
      \nHow do you convert ethene to ethane?
      \nAnswer:
      \nWhen a mixture of ethene and hydrogen is passed over heated nickel catalyst at 200\u00b0C, ethane is obtained.
      \n\\(\\mathrm{H}_{2} \\mathrm{C}=\\mathrm{CH}_{2}+\\mathrm{H}_{2} \\frac{\\mathrm{Ni}}{200^{\\circ} \\mathrm{C}} \\mathrm{CH}_{3}-\\mathrm{CH}_{3}\\)<\/p>\n

      Question 5.
      \nHow is propene obtained from propyl chloride ?
      \nAnswer:
      \nWhen propyl chloride is heated with alcoholic potash propene is obtained.
      \n\\(\\mathrm{CH}_{3}-\\mathrm{CH}_{2}-\\mathrm{CH}_{2} \\mathrm{Cl}+\\mathrm{KOH}_{(\\mathrm{alc})} \\stackrel{\\Delta}{\\longrightarrow} \\mathrm{CH}_{3}-\\mathrm{CH}=\\mathrm{CH}_{2}+\\mathrm{KCl}+\\mathrm{H}_{2} \\mathrm{O}\\).<\/p>\n

      Question 6.
      \nWhat is Wurtz reaction ? Give example.
      \nAnswer:
      \nWhen alkyl halides are heated with sodium metal in ether medium higher alkanes are formed. This reaction is known as Wurtz reaction and employed for the synthesis of higher alkanes containing even number of carbon atoms.
      \n\"1st<\/p>\n

      Question 7.
      \nHow is Methane prepared from sodium acetate ?
      \nAnswer:
      \nDecarboxylation : When sodium salt of carboxylic acid is heated with soda lime (mixture of sodium hydroxide and calcium oxide), an alkane containing one carbon atom less than parent carboxylic acid is formed. This reaction is called decarboxylation.
      \n\"1st<\/p>\n

      Question 8.
      \nHow is alkane prepared from Kolbe’s electrolytic method ?
      \nAnswer:
      \nA concentrated sodium salt of a carboxylic acid is electrolysed. The alkane is formed at the anode as one of the products. This process is called Kolb’e electrolysis.
      \n\"1st
      \n\"1st<\/p>\n

      Question 9.
      \nWhat is Pyrolysis ? Give example.
      \nAnswer:
      \nThe decomposition of higher alkane into a mixture of lower alkanes, alkenes, etc by the application of heat is called pyrolysis or cracking.
      \n\"1st<\/p>\n

      Question 10.
      \nWhat is Aromatisation ? Give example.
      \nAnswer:
      \nHexane or higher akanes when heated in presence of vanadium pentoxide (V2<\/sub>O5<\/sub>), molybdenium oxide (MO2<\/sub>O3<\/sub>) or chromium oxide (Cr2<\/sub>O3<\/sub>) supported on alumina (Al2<\/sub>O3<\/sub>) at 800 K and 10-20 atm pressure give benzene or its alkyl derivatives with the liberation of hydrogen. This dehydrogenation process which involves cyclis^ion of alkanes is known as aromatization.
      \n\"1st<\/p>\n

      Question 11.
      \nWhat is isomerisation ? Give example.
      \nAnswer:
      \nWhen unbrached alkanes are heated with anhydrous aluminium chloride and hydrogen chloride, isomeric branched alkanes are formed. This process is called isomerisation.
      \n\"1st<\/p>\n

      Question 12.
      \nWhat is Geometrical isomerism ?
      \nAnswer:
      \nCompounds having same molecular formula and structural formula but differ in the spatial arrangement of atoms or group of atoms due to restricted rotation of carbon carbon double bond.<\/p>\n

      Question 13.
      \nWhat are the conditions for Geometrical isomerism ?
      \nAnswer:<\/p>\n

        \n
      • The molecule should contain double bond.<\/li>\n
      • Each carbon atom joined by the double bond, must be attached to two different groups.<\/li>\n<\/ul>\n

        Question 14.
        \nWhat is Ozonalysis ? Give example.
        \nAnswer:
        \nThe ozonolysis of alkenes involves addition of ozone molecule to carbon-carbon double bond of alkenes to form ozonide. This follows hydrolysis of the ozonoide by H2<\/sub>O\/Zn to yield corresponding aldehydes and \/ or ketones. The addition of ozone to alkene followed by hydrolysis is known as ozonolysis.
        \n\"1st<\/p>\n

        Question 15.
        \nHow is ethene prepared ?
        \nAnswer:
        \nWhen 1, 2 – dihaloalkanes (vicinal dihalides) are heated with zinc metal in presence of methanol corresponding alkenes are formed. This reaction is called dehalogenation.
        \n\\(\\mathrm{Br}-\\mathrm{CH}_{2}-\\mathrm{CH}_{2}-\\mathrm{Br}+\\mathrm{Zn} \\frac{\\mathrm{CH}_{3} \\mathrm{OH}}{\\text { heat }} \\mathrm{CH}_{2}=\\mathrm{CH}_{2}+\\mathrm{ZnBr}_{2}\\)<\/p>\n

        \"KSEEB<\/p>\n

        Question 16.
        \nWhat are the uses of LDPE and HDPE ?
        \nAnswer:
        \nLDPE is used for<\/p>\n

          \n
        • making transparent films for packaging garments and food,<\/li>\n
        • as an insultor.<\/li>\n<\/ul>\n

          HDPE is used for<\/p>\n

            \n
          • making crates and large boxes<\/li>\n
          • production of carry bags, containers, house hold articles and toys.<\/li>\n<\/ul>\n

            Question 17.
            \nWhat happens when Ammonical solution of silver Nitrate treated with Acetylene ?
            \nAnswer:
            \nAcetylene when passed through an ammonical solution of silver nitrate (Toallen’s reagent) white solid of silver acetylide is separated.
            \n\"1st<\/p>\n

            Question 18.
            \nGive four examples for isomerism in Arenes.
            \nAnswer:
            \n\"1st<\/p>\n

            Question 19.
            \nGive three examples for fused polycyclic arene
            \nAnswer:
            \n\"1st<\/p>\n

            Question 20.
            \nState Markownkoff s rule.
            \nAnswer: When an unsymmetrical molecule adds to an unsymmetrical alkene, the negative part of the adding molecule adds to the carbon atom involved in the double bond, containing the least number of hydrogen atoms. Thus according to Markonwkoff’s rule the addition takes place as follows :
            \n\"1st<\/p>\n

            1st PUC Chemistry Hydrocarbons Four\/Five Mark Questions and Answers<\/h3>\n

            Question 1.
            \nExplain the action of chlorine on methane in the presence of sunlight.
            \nAnswer:
            \nMethane reacts with chlorine in the presence of diffused sunlight to give methyl chloride, methylene chloride, chloroform and carbon tetrachloride.
            \n\"1st<\/p>\n

            Question 2.
            \nExplain the mechanism of chlorination of methane, according to Free Radical.
            \nAnswer:
            \nMechanism of chlorination of methane involves three types.
            \n1. Initiation : Chlorine absorbs energy and undergoes homolysis to give chlorine free radicals.
            \n\\(\\mathrm{Cl}-\\mathrm{Cl} \\stackrel{\\mathrm{hy}}{\\longrightarrow} 2 \\mathrm{Cl}^{\\bullet}\\)<\/p>\n

            Step 2 : Propagation : Chlorine free radical reacts with methane to give methyl free radical.
            \n\\(\\mathrm{Cl}^{\\bullet}+\\mathrm{CH}_{4} \\longrightarrow \\mathrm{CH}_{3}^{\\bullet}+\\mathrm{HCl}\\)
            \nThe methyl free radical reacts with chlorine to form methyl chloride and chlorine free radical.
            \n\"1st<\/p>\n

            Step 3 : Termination : Free radials combine to form stable products.
            \n\"1st<\/p>\n

            Question 3.
            \nExplain the mechanism of addition of hydrogen bromide to propene.
            \nAnswer:
            \nThe mechanism of addition of hydrogen bromide to propene takes place in three steps. Step 1: Hydrogen bromide dissociates into H+<\/sup> and Br-
            \nH-Br \u2192 H+<\/sup>+Br–<\/sup><\/p>\n

            Step 2 : The electrophile H+ attacks propene to form carbocation.
            \n\"1st
            \nof the two carbocations (I) and (II), carbocations (I) is more stable and is formed more readily.<\/p>\n

            Step 3 : The nucleophile Br attacks the carbocation (I) to give 2 – bromopropane.
            \n\"1st<\/p>\n

            \"KSEEB<\/p>\n

            Question 4.
            \nHow is the manufacture of LDPE & HDPE ?
            \nAnswer:
            \nLow density polythene is manufactured by compressing ethane under very high pressure (1500-2000 atmospheres) at about 475 K in the presence of a small amount of oxygen as catalyst.
            \n\"1st<\/p>\n

            High density polythene is obtained by passing ethene under pressure of 6 atmospheres at about 340 K into heptane, an inert solvent containing Zielgler-Natta catalyst (triethyl) aluminium and titanium tetrachloride)
            \n\"1st<\/p>\n

            Question 5.
            \nGive four uses of aceylene.
            \nAnswer:<\/p>\n

              \n
            1. Oxyacetylene flame is used for cutting and welding of metals.<\/li>\n
            2. Acetylene and its derivatives are widely used in synthetic organic chemistry for synthesis of cis and trans-alkenes, methyl ketones, etc.<\/li>\n
            3. Acetylene is used as illuminant in hawker’s lamp and in light houses.<\/li>\n
            4. Acetylene is used for ripening of fruits and vegetables.<\/li>\n
            5. Acetylene is used for manufacture of ethyl alcohol, acetaldehyde, acetic acid, vinyl plastics, synthetic rubbers such as Buna-N and synthetic fibres such as Orlan.<\/li>\n<\/ol>\n

              Question 6.
              \nGive 4 uses of ethene.
              \nAnswer:<\/p>\n

                \n
              1. Lower members of the family are used as fuels and illuminants.<\/li>\n
              2. Alkenes and substituted alkenes upon polymerization form a number of useful polymers such as polythene, PVC, Teflon, orlon, etc.,<\/li>\n
              3. Ethene is employed for preparation of ethyl alcohol and ethylene glycol (anti-freeze).<\/li>\n
              4. Ethylene is used for artificial ripening of green fruits.<\/li>\n
              5. Ethylene also used in oxygen-ethylene flame for cutting and welding of metals.<\/li>\n<\/ol>\n

                Question 7.
                \nGive four uses of methane.
                \nAnswer:<\/p>\n

                  \n
                1. Methane in the form of natural gas (CNG) is used for running scooters, cars, buses, etc., LPG (Mixture of butane and isobutene) is used as a fuel in homes as well as in industry.<\/li>\n
                2. Methane is used to make carbon black which is used in the manufacture of printing inks, paints and automobile tyres.<\/li>\n
                3. Cataltic oxidation of alkanes gives alcohols, aldehydes an carboxylic acids.<\/li>\n
                4. Higher alkanes in form of gasoline, kerosene oil, diesel, lubricating oils and paraffin wax are widely used.<\/li>\n
                5. Methane is used for manufacture halogen containing compounds such as CH2<\/sub>Cl2<\/sub> , CHCl3<\/sub> , CCl4<\/sub> etc. which are used as solvents both in laboratory and industry.<\/li>\n<\/ol>\n

                  Question 8.
                  \nGive the structural elucidation of benzene.
                  \nAnswer:
                  \n1. From elemental analysis and molecular mass determination, the molecular formula of benzene is found to be C6<\/sub>H6<\/sub>.<\/p>\n

                  2. On the basis of molecular formula benzene is highly unsaturated compound.<\/p>\n

                  3. Benzene does not show alkene properties. Benzene is quite stable. It does not decolourise cold aqueous solution of potassium paramanganate.<\/p>\n

                  4. Benzene shows cyclic structure,
                  \n(a) Benzene contains three double bonds. Benzene adds three moles of hydrogen in presence of nickel catalyst to form cyclohexane.<\/p>\n\\(\\mathrm{C}_{6} \\mathrm{H}_{6}+3 \\mathrm{H}_{2} \\frac{180^{\\circ} \\mathrm{C}}{\\mathrm{Ni}} \\mathrm{C}_{6} \\mathrm{H}_{12}\\)\n

                  (b) All the six hydrogen atoms in benzene are identical – benzene reacts with bromine in presence of FeBr3 catalyst to form monobromobenzene.<\/p>\n\\(\\mathrm{C}_{6} \\mathrm{H}_{6}+\\mathrm{Br}_{2} \\stackrel{\\mathrm{FeBr}_{3}}{\\longrightarrow} \\mathrm{C}_{6} \\mathrm{H}_{5} \\mathrm{Br}+\\mathrm{HBr}\\)\n

                  5. Kekule proposed benzene is a planar ring structure with alternate single and double bonds.
                  \n\"1st<\/p>\n

                  6. To overcome this drawback, Kekule suggested that benzene is a mixture of two forms, which are in rapid oscillation.
                  \n\"1st<\/p>\n

                  7. It is found that the bond length in benzene is same for all C-C bonds (0.139 nm). This lies between C-C single bond (0.154 nm) and C-C double bond length (0.134 nm).<\/p>\n

                  8. Resonance structure: Resonance hybrid is more stable than structure 1 and 2. The stability of benzene due to resonance is so great that n bonds of the molecule will normally resist breaking. This explain the stability of benzene.
                  \n\"1st<\/p>\n

                  Question 9.
                  \nExplain the mechanism of halogenation or chlorination of benzene.
                  \nAnswer:
                  \nHalogenation: Benzene reacts with chlorine in the presence of FeCl3<\/sub> or AlCl3<\/sub> to form chlorobenzene.
                  \n\"1st
                  \nMachanism : This involves the following steps.<\/p>\n

                  Step 1: Generation of eiectrohile Cl – Cl + FeCl3<\/sub> \u2192 Cl+<\/sup> + \\(\\mathrm{FeCl}_{4}^{-}\\)
                  \nStep 2 : The electrophile Cl+<\/sup> attacks benzene ring to form a carbon cation which is resonance stabilised.
                  \n\"1st
                  \nStep 3 : Loss of a proton to give chlorobenzene. The proton is removed by FeCU.
                  \n\"1st<\/p>\n

                  \"KSEEB<\/p>\n

                  Question 10.
                  \nExplain the mechanism of nitration of benzene.
                  \nAnswer:
                  \nNitration benzene reacts with a mixture of concentrated nitric acid and concentrated sulphuric acid at 50\u00b0C to form nitrobenzene.
                  \n\"1st
                  \nMechanism : This involves the following steps.
                  \nStep 1: Generation of electrophile nitronium ion \\(\\mathrm{NO}_{2}^{+}\\)
                  \n\\(\\mathrm{HNO}_{3}+2 \\mathrm{H}_{2} \\mathrm{SO}_{4} \\longrightarrow \\mathrm{NO}_{2}^{+}+\\mathrm{H}_{3} \\mathrm{O}^{+}+2 \\mathrm{HSO}_{4}^{-}\\)<\/p>\n

                  Step 2 : The electrophile NO2<\/sub> attacks the benzene ring to form a carbocation which is resonance stabilized.
                  \n\"1st<\/p>\n

                  Step 3 : Loss of a proton to give nitrobenzene. The proton is removed by \\(\\mathrm{HSO}_{4}^{-}\\)
                  \n\"1st<\/p>\n

                  Question 11.
                  \nExplain the mechanism of sulphonation of benzene?
                  \nAnswer:
                  \nSulphonation : Benzene reacts with concentrated sulphuric acid at 80\u00b0C to form benzene sulphoric acid.
                  \n\"1st
                  \nMechanism : This involves the following steps.<\/p>\n

                  Step 1: Generation of electrophile SO3<\/sub>.
                  \n\\(2 \\mathrm{H}_{2} \\mathrm{SO}_{4} \\rightleftharpoons \\mathrm{SO}_{3}+\\mathrm{H}_{3} \\mathrm{O}^{+}+\\mathrm{HSO}_{4}^{-}\\)<\/p>\n

                  Step 2 : The electrophile SO3<\/sub> attacks the benzene ring to form a carbocation
                  \n\"1st
                  \nStep 3: Loss of a proton to from a sulphonate ion. The proton is removed by \\(\\mathrm{HSO}_{4}^{-}\\)
                  \n\"1st<\/p>\n

                  Step 4 : Addition of proton to give benzene sulphonic acid.
                  \n\"1st<\/p>\n

                  Question 12.
                  \nExplain the mechanism of Friedel craft alkylation of benzene.
                  \nAnswer:
                  \nFriedel – Craft alkylation reaction Benzene reacts with methyl chloride in presence of anhydrous aluminium chloride to form toluene. This is called Friedel-Crafts alkylation reaction.
                  \n\"1st
                  \nThe mechanism of Friedel Craft\u2019s alkylation reaction involves the following steps:<\/p>\n

                  \"KSEEB<\/p>\n","protected":false},"excerpt":{"rendered":"

                  You can Download Chapter 13 Hydrocarbons Questions and Answers, Notes, 1st PUC Chemistry Question Bank with Answers Karnataka State Board Solutions help you to revise complete Syllabus and score more marks in your examinations. Karnataka 1st PUC Chemistry Question Bank Chapter 13 Hydrocarbons 1st PUC Chemistry Hydrocarbons One Mark Questions and Answers Question 1. What …<\/p>\n","protected":false},"author":5,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[81],"tags":[],"jetpack_sharing_enabled":true,"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/posts\/8801"}],"collection":[{"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/users\/5"}],"replies":[{"embeddable":true,"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/comments?post=8801"}],"version-history":[{"count":0,"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/posts\/8801\/revisions"}],"wp:attachment":[{"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/media?parent=8801"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/categories?post=8801"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/kseebsolutions.guru\/wp-json\/wp\/v2\/tags?post=8801"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}