CBSE Class 11 Chemistry Hydrocarbons Assignment

Question-Calcium carbide when treated with water gives :

(a) ethylene 

(b) methane 

(c) acetylene 

(d) ethane 

Answer-(c)

Question-Aromatic compounds burn with sooty flame because 

(a) they have a ring structure of carbon atoms 

(b) they have a relatively high percentage of hydrogen 

(c) they have a relatively high percentage of carbon 

(d) they resist reaction with oxygen of air 

Answer-(c)

Question-Benzene can be obtained in the reaction 

(a) Ethene + 1, 3-butadiene 

(b) Trimerisation of ethyne 

(c) Reduction of PhCHO 

(d) All of these 

Answer-(b)

Question-Which of these will not react with acetylene? 

(a) NaOH 

(b) Ammonical AgNO₃ 

(c) Na 

(d) HCl. 

Answer-(a)

Question-The benzene molecule contains

(a) 6 sp² hybrid carbons 

(b) 3 sp² hybrid carbons 

(c) 6 sp³ hybrid carbons 

(d) 3 sp³ hybrid carbons

Answer-(a)

Question-When acetylene is passed over heated iron tube, the product obtained is – 

(a) C₂H₂ 

(b) C₄H₄ 

(c) C₆H₆

(d) C₈H₈

Answer-(c)

Question-When propyne reacts with aqueous H₂SO₄ in the presence of HgSO₄, the major product is 

(a) Propanal

(b) Propyl hydrogen sulphate 

(c) Acetone 

(d) Propanol

Answer-(c)

Question-Propyne on polymerisation gives 

(a) Mesitylene 

(b) Benzene 

(c) Ethyl benzene 

(d) Propyl benzene

Answer-(a)

Question-When acetylene is passed through dil. H₂SO₄ in presence of HgSO₄, the compound formed is 

(a) ether 

(b) acetaldehyde 

(c) acetic acid 

(d) ketone

Answer-(b)

Question-What happens when a mixture of acetylene and hydrogen is passed over heated Lindlar’s catalyst ? 

(a) Ethane and water are formed 

(b) Ethylene is formed 

(c) Acetylene and ethane are formed 

(d) None of these

Answer-(b)

Question-Which of the following polymer can be used as electrodes in batteries ? 

(a) Polypropene 

(b) Polyacetylene 

(c) Polyethene 

(d) Polyisoprene

Answer-(b)

Question-Which one of the following is a non-benzenoid aromatic compound? 

(a) Aniline 

(b) Benzoic acid 

(c) Naphthalene 

(d) Tropolone 

Answer-(d)

Question-The ring structure of benzene was proposed by 

(a) Faraday

(b) Davy 

(c) Kekule 

(d) Wohler 

Answer-(c)

Question-Which of the following reaction is shown by alkynes ? 

(a) Addition 

(b) Substitution 

(c) Polymerization 

(d) All of these

Answer-(d)

Question-Benzene was discovered by 

(a) Ramsay 

(b) Dalton 

(c) Faraday 

(d) Priestley 

Answer-(c)

Question-Select the true statement about benzene amongst the following 

(a) Because of unsaturation benzene easily undergoes addition 

(b) There are two types of C – C bonds in benzene molecule 

(c) There is cyclic delocalisation of pi-electrons in benzene 

(d) Monosubstitution of benzene gives three isomeric products.

Answer-(c)

Question-But–2–yne on chlorination gives 

(a) 1 –chlorobutane 

(b) 1, 2 –dichlorobutane 

(c) 1, 1, 2, 2 –tetrachlorobutane 

(d) 2, 2, 3, 3 –tetrachlorobutane

Answer-(d)

119. Carbon atom in benzene molecule is inclined at an angle of 

(a) 120° 

(b) 180° 

(c) 109° 28' 

(d) 60° 

Answer-(a)

Question-Nitration of benzene by nitric acid and sulphuric acid is 

(a) Electrophilic substitution 

(b) Electrophilic addition 

(c) Nucleophilic substitution 

(d) Free radical substitution

Answer-(a)

Question-Chlorobenzene is o, p-directing in electrophilic substitution reaction. The directing influence is explained by

(a) +M of Ph 

(b) +I of Cl 

(c) +M of Cl 

(d) +I of Ph 

Answer-(c)

Question-Six carbon atoms f benzene are of

(a) one type 

(b) two types 

(c) three types 

(d) six types 

Answer-(a)

Question-Which one of the following has the minimum boiling point ?

(a) 1-Butene 

(b) 1-Butyne 

(c) n- Butane 

(d) Isobutane 

Answer-(d)

Question- Catalytic hydrogenation of benzene gives 

(a) xylene 

(b) cyclohexane 

(c) benzoic acid 

(d) toluene 

Answer-(b)

More Question

ONE MARK QUESTIONS

1. Effect the following conversions:

a) benzene to m-nitrochlorobenzene

b) benzene to acetophenone

c) ethane to benzene

d) 1-propanol to 2,3-dimethyl butane

e) Ethane to butane

f) Acetic acid to methane

g) Acetic acid to ethane

h) 2-propanol to hexane

i) ethyne to benzene

2. Which geometrical isomer of 2-hexene will have a higher boiling point? Why?

TWO MARKS QUESTIONS

1 Which of the following will exhibit geometrical isomer? Why?
a) 1-pentene
b) 2-pentene

2 Give chemical equation fo the following reactions.
a) Ethyne is passed through red hot copper tube.
b) Propane is treated with Cl₂ in diffused sunlight

3 How will you distinguish between 
a) propane and propene
b) propene and propyne
c) 1-butyne and 2-butyne
d) propane and propyne

4 Explain why
a) Nitro group is meta directive
b) Acetylenic hydrogen is acidic

5 Draw
a) Newman projection for the staggered and eclipsed conformations in propane
b) Saw Horse projection for the staggered and eclipsed conformations in butane between C₁ and C₂.

6 Write the structure and classify the carbon atoms as primary, secondary and tertiary in 2, 3, 3-trimethyl pentane

7 An alkene on ozonolysis gives a mixture of ethanal and pentan-3-one. Write the structure and IUPAC name of the alkene.

8 Explain Markovnikov rule with a suitable example.

THREE MARKS QUESTIONS

1 What happens when?
a) Acetylene is treated with ammoniacal AgNO₃ solution.
b) 2-methyl-2-butene is treated with alk. KMnO₄ at 373K.
c) 2-methylpropene is treated with bromine water

2 Give reasons:
a) Benzene undergoes electrophilic substitution reactions.
b) Alkenes undergo electrophilic addition reactions easily.
c) Nitration of toluene is easier than benzene

3 Explain the following reactions.
a) Friedel Craft acylation.
b) Kolbe’s electrolysis
c) Wurtz reaction