Изомерами являются:
1) CH3 - C = O и CH3-CH2-C=O
H H
2) CH3-CH2-CH2-C=O и CH3-CH-C=O
H CH3 H
3) CH3-C-CH2-CH3 и CH3-C-CH2-CH2-CH3
" "
O O
4) CH3-C-CH3 и CH3-C-CH2-CH3
" "
O O