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#### Hydrocarbons Book Back Questions

11th Standard

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Chemistry

Time : 00:45:00 Hrs
Total Marks : 30
6 x 1 = 6
1. The correct statement regarding the comparison of staggered and eclipsed conformations of ethane is

(a)

the eclipsed conformation of ethane is more stable than staggered conformation even though the eclipsed conformation has torsional strain

(b)

the staggered conformation of ethane is more stable than eclipsed conformatio, because staggered conformation has no torsional strain

(c)

the staggered conformation of ethane is less stable than eclipsed conformation, because staggered conformation has torsional strain

(d)

the staggered conformation of ethane is less stable than eclipsed conformation, because staggered conformation has no torsional strain

2. An alkyl bromide (A) reacts with sodium in ether to form 4, 5– diethyloctane, the compound (A) is

(a)

CH3 (CH2)3 Br

(b)

CH3(CH2)5 Br

(c)

CH3(CH2)3 CH(Br)CH3

(d)

${ CH }_{ 3 }-{ \left( { CH }_{ 2 } \right) }_{ 3 }-CH\left( Br \right) -\underset { \overset { { | } }{ { CH }_{ 3 } } }{ { CH }_{ 3 } }$

3. The C – H bond and C – C bond in ethane are formed by which of the following types of overlap

(a)

sp3 – s and sp3 – sp3

(b)

sp2 – s and sp2 – Sp2

(c)

sp – sp and sp – sp

(d)

p – s and p – p

4. The general formula for cyclo alkanes

(a)

CnHn

(b)

CnH2n

(c)

Cn H2n–2

(d)

Cn H2n+2

5. The compound that will react most readily with gaseous bromine has the formula

(a)

C3H6

(b)

C2H2

(c)

C4H10

(d)

C2H4

6. Which among the following alkenes on reductive ozonolysis produces only propanone?

(a)

2 – Methyl propene

(b)

2 – Methyl but – 2 - ene

(c)

2, 3 – Dimethyl but – 1 – ene

(d)

2, 3 – Dimethyl but – 2 – ene

7. 7 x 2 = 14
8. How is propyne prepared from an alkyene dihalide?

9. An alkylhalide with molecular formula C6H13Br on dehydro halogenation gave two isomeric alkenes X and Y with molecular formula C6H12. On reductive ozonolysis, X and Y gave four compounds CH3COCH3, CH3CHO, CH3CH2CHO and (CH3)2 CHCHO. Find the alkylhalide.

10. How does Huckel rule help to decide the aromatic character of a compound.

11. Suggest a simple chemical test to distinguish propane and propene.

12. What happens when isobutylene is treated with acidified potassium permanganate?

13. Identify A and B.

14. How will you distinguish 1 – butyne and 2 – butyne?

15. 2 x 5 = 10
16. Give IUPAC names for the following compounds
1) CH3 – CH = CH – CH = CH – C ≡ C – CH3
2)
3) (CH3)3 C – C ≡ C – CH (CH3)2
4) ethyl isopropyl acetylene
5) CH ≡ C – C ≡ C – C ≡ CH

17. Identify the compound A, B, C and D in the following series of reactions

Write short notes on ortho, para directors in aromatic electrophilic substitution reactions.