a) 2-chlorobutan, 1-bromopropan, 2-bromopropan, 2-metylopropan, 2,3-dimetylobutan, 2,2-dibromopropan

b) 1,1-dichloroetan, 1,2-dichloroetan, 1.4-dijodobutan, 1,3-dichlorobutan, 2,2-dimetylopropan,