Chemistry Class 11 NCERT Solutions: Chapter 13 Hydrocarbons Part 8 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Q: 13. How will you convert benzene into

(I) p-nitrobromobenzene

(II) m-nitrochlorobenzene

(III) p -nitrotoluene

(Iv) Acetophenone

Answer

(I) Benzene can be converted into p-nitrobromobenzene as:

Q_13_Ans_I_Structure of P-Nitrobromobenzene

(II) Benzene can be converted into m-nitrochlorobenzene as:

Q_13_Ans_II_Structure of M-Nitrochlorobenzene

(III) Benzene can be converted into p-nitrotoluene as:

Q_13_Ans_III_Structure of P-Nitrotoluene

(IV) Benzene can be converted into acetophenone as:

Q_13_Ans_IV_Structure of Acetophenon

Q: 14. In the alkane , identify carbon atoms and give the number of H atoms bonded to each one of these.

Answer:

Q_14_Ans_Structure of Carbon Atoms and Number of H Atoms

Carbon atoms are those which are bonded to only one carbon atom i.e.. , they have only one carbon atom as their neighbour. The given structure has five 1° carbon atoms and fifteen hydrogen atoms attached to it.

Carbon atoms are those which are bonded to two carbon atoms i.e.. , they have two carbon atoms as their neighbours. The given structure has two carbon atoms and four hydrogen atoms attached to it. carbon atoms are those which are bonded to three carbon atoms i.e.. , they have three carbon atoms as their neighbours. The given structure has one carbon atom and only one hydrogen atom is attached to it.

Q: 15. What effect does branching of an alkane chain has on its boiling point?

Answer

Alkanes experience inter-molecular Van der Waals forces. The stronger the force, the greater will be the boiling point of the alkane. As branching increases, the surface area of the molecule decreases which results in a small area of contact. As a result, the Van der Waals force also decreases which can be overcome at a relatively lower temperature. Hence, the boiling point of an alkane chain decreases with an increase in branching.

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