1,1-diisopropylethene < (Z)-1,2-diisopropylethene < (E)-1,2-diisopropylethene
The compounds are listed in order of increasing stability.
Also, what does the C=C-C bond angle have do to with stability? And the order of increasing C=C-C is 1,1 < E < Zwhy is it different than question 1?