Which is expected to react most readily with bromine?

• (A) CH₃CH₂CH₃
• (B) CH₂=CH₂
• (C) CH≡CH
• (D) CH₃-CH=CH₂

To determine which compound reacts most readily with bromine, we need to consider the types of bonds present in each option. Bromine typically reacts with alkenes and alkynes through an addition reaction.

Analyzing the Options

• (A) CH₃CH₂CH₃: This is an alkane with only single bonds, making it less reactive with bromine.
• (B) CH₂=CH₂: This is an alkene, which has a double bond. Alkenes react readily with bromine.
• (C) CH≡CH: This is an alkyne with a triple bond. Alkynes can also react with bromine, but typically less readily than alkenes.
• (D) CH₃-CH=CH₂: This is another alkene, which will also react readily with bromine.

Conclusion

Among these options, both (B) and (D) are alkenes and will react with bromine. However, (B) CH₂=CH₂ is the simplest alkene and is expected to react most readily with bromine due to its less steric hindrance and higher reactivity. Therefore, the answer is (B) CH₂=CH₂.