Chemistry Class 12 NCERT Solutions: Chapter 10 Haloalkanes and Haloarenes Part 4

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Q: 4. Which one of the following has the highest dipole moment?

(i)

(ii)

(iii)

Answer:

(i)

Q 4 Dichloromethane

Q 4 Dichloromethane

Q 4 Dichloromethane

Dichloromethane

(ii)

Q 4 ii Chloroform

Q 4 Ii Chloroform

Q 4 ii Chloroform

Chloroform

(iii)

Q 4 iii Carbon tetrachloride

Q 4 Iii Carbon Tetrachloride

Q 4 iii Carbon tetrachloride

Carbon tetrachloride

is a symmetrical molecule. Therefore, the dipole moments of all four bonds cancel each other. Hence, its resultant dipole moment is zero.

As shown in the above figure, in , the resultant of dipole moments of two bonds is opposed by the resultant of dipole moments of one bond and one bond. Since the resultant of one bond and one bond dipole moments is smaller than two bonds, the opposition is to a small extent. As a result, has a small dipole moment of .

On the other hand, in case of , the resultant of the dipole moments of two bonds is strengthened by the resultant of the dipole moments of two bonds. As a result, has a higher dipole moment of than i.e., has the highest dipole moment.

Hence, the given compounds can be arranged in the increasing order of their dipole moments as:

Q: 5. A hydrocarbon does not react with chlorine in dark but gives a single monochord compound in bright sunlight. Identify the hydrocarbon.

Answer:

A hydrocarbon with the molecular formula, belongs to the group with a general molecular formula . Therefore, it may either be an alkene or a cycloalkane. Since hydrocarbon does not react with chlorine in the dark, it cannot be an alkene. Thus, it should be a cycloalkane.

Further, the hydrocarbon gives a single monochloro compound, by reacting with chlorine in bright sunlight. Since a single monochloro compound is formed, the hydrocarbon must contain atoms that are all equivalent. Also, as all atoms of a cycloalkane are equivalent, the hydrocarbon must be a cycloalkane. Hence, the said compound is cyclopentane.

Q 5 Cyclopentane (C5H10) and Mono-chlorocyclopentane (C5H9Cl)

Q 5 Cyclopentane (C5H10) and Mono-Chlorocyclopentane (C5H9Cl)

Q 5 Cyclopentane (C5H10) and Mono-chlorocyclopentane (C5H9Cl)

Q: 6. Write the isomers of the compound having formula .

Answer:

There are four isomers of the compound having the formula . These isomers are given below.

(A)

Q 6 A 1-Bomobutane

Q 6 a 1-Bomobutane

Q 6 A 1-Bomobutane

1-Bomobutane

(B)

Q 6 B 2-CBromobutane

Q 6 B 2-CBromobutane

Q 6 B 2-CBromobutane

2-CBromobutane

(C)

Q 6 C 1-Bromo-2-Methylpropane

Q 6 C 1-Bromo-2-Methylpropane

Q 6 C 1-Bromo-2-Methylpropane

1-Bromo-2-Methylpropane

(D)

Q 6 D 2-Bromo-2-methylpopane

Q 6 D 2-Bromo-2-Methylpopane

Q 6 D 2-Bromo-2-methylpopane

2-Bromo-2-methylpopane