Question

The boiling points of methyl bromide (1), ethyl bromide(II), n - propyl bromide (III) and n - butyl bromide (IV) decrease in the order : (1) I > II > III > IV (2) IV > III > II > I (3) I > III > II > IV (4) III > IV>I> II​

Answer 1

option 4 is correct answer

Answer 2

The order of decreasing boiling point is as follows

butyl 1 bromide >n propyl bromide > ethyl bromide > methyl bromide

i.e. Option (2) is the correct answer IV > III > II > I

Explanation:

• SN′1  reaction is based on the presence of a leaving group to give a carbocation, then the nucleophile will attack depending on the alky group attached on it.
• So carbocation must be stable and its  
• Carbocation Stability increases with an approach for reactivity will depend on the alkyl group and it increases with the  substitution of carbon
• i.e. tertiary > secondary >primary

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