Answer:
The correct answer is option c.
Step-by-step explanation:
The boiling point of chloromethane is -24.2 degree C, the boiling point of 2-chloropropane is 35 degrees C, the boiling point of chloroethane is 12.3 degrees C, and the boiling point of 2-chloro-2-methylpropane is 51 degrees C. Thus, the order of decreasing boiling point is 2-chloro-2-methylpropane>2-chloropropane>chloroethane>chloromethane. Hence, the correct answer is option c.