The order of ease of dehydrohalogenation by alcoholic $\mathrm{KOH}$ for ethyl bromide, isopropyl bromide and tert-butyl bromide is:

1. Aethyl bromide $>$ isopropyl bromide $>$ tert-butyl bromide
2. Bisopropyl bromide $>$ tert-butyl bromide $>$ ethyl bromide
3. Call three react at the same rate
4. Dtert-butyl bromide $>$ isopropyl bromide $>$ ethyl bromide