Justify and arrange the following compounds of each set in increasing order of reactivity towards the asked displacement :
1-Bromobutane, 2-Bromobutane, 2-Bromo-2-Methylpropane (`S_(N)2` reaction)

Explanation

2-Bromo-2-Methylpropane `lt` 2-Bromobutane `lt` 1-Bromobutane
The nucleophile faces the maximum hindrance from the bulky groups in 2-Bromo-2Methylpeopane followed by 2-Bromobutane and 1-Bromobutane. Hence the above order.