Question

Which one of the following molecules gives four isomeric monochlorides on photochemical chlorination?

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• A. 2-Methylpropane
• B. n-Butane
• C. 2-Methylbutane
• D. 2,3-Dimethylbutane
• E. Propane

Answer 1

The Correct Option is C

Photochemical chlorination involves the substitution of hydrogen atoms with chlorine in the molecule. The number of isomeric monochlorides formed depends on the number of distinct hydrogen atoms in the molecule.

For 2-methylbutane, the possible sites for chlorination are at four positions:  
1. The 1-position on the main chain  
2. The 2-position on the main chain  
3. The 3-position on the main chain  
4. The methyl group attached at position 2  

This gives four distinct monochlorides. In contrast, other molecules like 2-methylpropane and propane do not have enough distinct sites to give four different monochlorides.

The correct option is (C) : 2-Methylbutane

Answer 2

2-Methylbutane 

Explanation:

When a molecule undergoes photochemical chlorination, chlorine atoms replace hydrogen atoms in different positions of the molecule, resulting in the formation of isomers. The number of isomers depends on the number of unique positions for chlorine substitution.

Let's analyze each option:

• 2-Methylpropane: This molecule only has two unique positions for chlorination (the two hydrogens on the carbon chain), so it can form two isomers.
• n-Butane: n-Butane has three unique positions for chlorination, resulting in three isomers.
• 2-Methylbutane: This molecule has four unique positions for chlorination, resulting in four isomeric monochlorides. These positions are the hydrogens on the carbon chain and the methyl group.
• 2,3-Dimethylbutane: This molecule has fewer positions for chlorination and can form fewer isomers.
• Propane: Propane only has two unique positions for chlorination, leading to two isomers.

Therefore, the correct answer is 2-Methylbutane, which gives four isomeric monochlorides on photochemical chlorination.