Chemistry

Hydrocarbons

Question:

Which type of isomerism is exhibited by but-l-yne and but-2-yne?

Answer:

Position isomerism.

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Hydrocarbons

Q 1.

In the alkane, CH3CH2—C(CH3)2—CH2—CH(CH3)2, identify 1 °, 2 °, 3 ° carbon atoms and give the number of H-atoms bonded to each one of these.

Q 2.

Convert ethylene to ethane.

Q 3.

What is the hybridisation of central carbon in 1,2-propadiene (CH2=C=CH2)?

Q 4.

Nucleophiles and electrophiles are reaction intermediates having electron rich and electron deficient centres respectively. Hence, they tend to attack electron deficient and electron rich centres respectively. Classify the following species as electrophiles and nucleophiles.
ncert-exemplar-problems-class-11-chemistry-chapter-13-hydrocarbons-46

Q 5.

What happens when ethanol is heated with cone. H2SO4?

Q 6.

Explain the term aromaticity. What are the necessary conditions for any compound to show aromaticity?

Q 7.

What are conformations?

Q 8.

Write the IUPAC names of the following compounds.
(i) (CH3)CCH2C(CH3)3    (ii) (CH3)2C(C2H5)2

Q 9.

Which is more acidic: ethene or ethyne and why?

Q 10.

The molecules having dipole moment are________ .
(a) 2,2-Dimethylpropane                                            
(b) trans-Pent-2-ene
(c) cw-Hex-3-ene            
(d) 2,2,3,3-Tetramethylbutane

Q 11.

Which of the following are correct?
(a) CH3 – O – CH+2 is more stable than CH3 – CH+2
(b) (CH3)2CH+ is less stable than CH3 – CH2 – CH+2
(c) CH2 = CH – CH+2 is more stable than CH3 – CH2 – CH+2
(d) CH2 = CH+ is more stable than CH3 – CH+2
 

Q 12.

The relative reactivity of 1 °, 2 ° and 3 ° hydrogens towards chlorination is 1: 3.8 : 5. Calculate the percentages of all monochlorinated products obtained from 2-methylbutane.
 

Q 13.

For the following compounds, write structural formulas and IUPAC names for all possible isomers having the number of double or triple bond as indicated:
(a) C4H8 (one double bond) (b) C5H8 (one triple bond)

Q 14.

How will you distinguish between propene and propane?

Q 15.

Arrange the following: HCl, HBr, HI, HF in order of decreasing reactivity towards alkenes.

Q 16.

What are Arenes ?

Q 17.

Why does the presence of a nitro group-make the benzene ring less reactive in comparison to the unsubstituted benzene ring? Explain.

Q 18.

What happens when benzene is treated with excess of Cl2 in presence of sunlight? Give chemical reaction.

Q 19.

Explain the following with examples:
(i) Wurtz reaction
(ii) Hydrogenation.

Q 20.

What is polymerization? Give an example.

Q 21.

Why is benzene extra-ordinarily stable though it contains three double bonds?

Q 22.

Out of benzene, m-dinitrobenzene and toluene which will undergo nitration most easily and why?

Q 23.

What happens when benzene is treated with acetyl chloride in presence of AlCl3?

Q 24.

Define resonance energy. What is resonance energy of benzene?

Q 25.

Discuss the shape of methane and ethane.

Q 26.

How will you demonstrate that double bonds of benzene are somewhat different from that of olefins?

Q 27.

Arrange the following carbanions in order of their decreasing stability.
(A) H3C-C ≡ C                                                                                
(B) H-C ≡ C
(C) H3C – CH2
(a) A>B>C
(b) B>A>C
(c) C>B>A
(d) C>A>B

Q 28.

Although benzene is highly unsaturated it does not undergo addition reactions. Why?

Q 29.

(a) Why are alkenes called unsaturated hydrocarbons?
(b) How will you test the presence of double bond in an alkene?
(c) Name the products formed when propene is subjected to ozonolysis.

Q 30.

Write structures of all the alkenes which on hydrogeneration give 2-methylbutane.

Q 31.

ncert-solutions-class-11th-chemistry-chapter-13-hydrocarbons-34

Q 32.

What is decarboxylation ? Give an example.

Q 33.

What is Lindlar’s catalyst? Give its use.

Q 34.

What will be the product obtained as a result of the following reaction and why?

ncert-exemplar-problems-class-11-chemistry-chapter-13-hydrocarbons-32

Q 35.

How will you distinguish between acetylene and ethylene?

Q 36.

An alkene ‘A’ contains three C-C, eight C-H σ bonds and one C-C Ï€ bond. ‘A' on ozonolysis gives two moles of an aldehyde of molar mass 44 u. Deduce IUPAC name of’A’.

Q 37.

How will you convert benzene into
(i) p-nitrobromobenzene (ii) m-nitrobromobenzene
 

Q 38.

Suggest the name of another Lewis acid instead of anhydrous aluminium chloride which can be used during ethylation of benzene.

Q 39.

What do you mean by pyrolysis?

Q 40.

Why are alkanes called paraffins?

Q 41.

What is Huckel rule?

Q 42.

Classify the following compounds into (i) alkanes (ii) alkenes (iii) alkynes (iv) arenes.  (a) C6H6 (b) C4H8 (C) C8H8 (d) C5H8 (e) C6H14

Q 43.

Discuss the preparation of alkanes by Wurtz reaction. What is the limitaHon of the reaction?

Q 44.

Which of the following alkenes on ozonolysis gives a mixture of ketones only?
ncert-exemplar-problems-class-11-chemistry-chapter-13-hydrocarbons-16

Q 45.

Rotation around carbon-carbon single bond of ethane is not completely free. Justify the statement.

Q 46.

An alkene ‘A’ contains three C—C, eight C—H, a-bonds, and one C—C n-bond. ‘A’ on ozonolysis gives two moles of an aldehyde of molar mass 44 u. Write the IUPAC name of’A’.

Q 47.

(a) What effect the branching of an alkane has on its melting point?
(b) Which of the following has highest boiling point?
(i) 2-methyl pentane
(ii) 2, 3-diethyl butane
(iii) 2, 2-dimethyl butane

Q 48.

How will you separate propene from propyne?

Q 49.

Which of the following reactions of methane is incomplete combustion?
ncert-exemplar-problems-class-11-chemistry-chapter-13-hydrocarbons-13

Q 50.

Which are the correct IUPAC names of the following compound
ncert-exemplar-problems-class-11-chemistry-chapter-13-hydrocarbons-20

(a) 5-(2′,2′-Dimethylpropyl)decane
(b) 4-Butyl-2,2-dimethylnonane
(c) 2,2-Dimethyl-4-pentyloctane
(d) 5-neo-Pentyldecane