Question 1

Which of the following compounds has the highest boiling point?

Accepted Answer

The boiling point of alkanes depends upon the molecular size and surface area. Straight-chain alkanes have larger surface areas compared to branched-chain isomers, leading to stronger van der Waals forces of attraction. Among the given options, n-pentane has a straight chain and thus the highest boi

Question 2

Wurtz reaction is used for the preparation of which of the following?

Accepted Answer

Wurtz reaction involves the treatment of an alkyl halide with sodium metal in dry ether to form higher alkanes containing an even number of carbon atoms. Therefore, it is specifically used for the preparation of higher alkanes from alkyl halides.

Question 3

Geometrical isomerism is exhibited by:

Accepted Answer

Geometrical isomerism is generally exhibited by alkenes containing a carbon-carbon double bond where the two carbon atoms are attached to different groups or atoms. Among the choices, 2-butene exhibits cis-trans (geometrical) isomerism due to restricted rotation around the carbon-carbon double bond.

Question 4

Addition of HBr to propene in the presence of peroxide follows which rule?

Accepted Answer

In the presence of organic peroxides (like benzoyl peroxide), the addition of unsymmetrical reagents like HBr to unsymmetrical alkenes like propene takes place via a free-radical mechanism, which yields anti-Markovnikov's product (1-bromopropane). This is also known as the peroxide effect or Kharasc

Question 5

Which of the following compounds is aromatic in nature according to Huckel's rule?

Accepted Answer

According to Huckel's rule, aromatic compounds must be cyclic, planar, completely conjugated, and contain (4n + 2) pi electrons, where n is an integer (0, 1, 2...). Benzene contains 6 pi electrons (n=1), is planar and cyclic, thus fulfilling all criteria for aromaticity.

Hydrocarbons — NCERT Class 11 Chemistry Important Questions & Revision Notes