- C5H10 có 10 đồng phân :CH2=CH-CH2-CH2-CH3(1), CH3-CH=CH-CH2-CH3 (2), CH2=C(CH3)-CH2-CH3 (3), CH3-CH(CH3)=CH-CH3 (4), CH3-CH(CH3)-CH=CH2 (5), xiclpentan (6), metylxiclobutan (7), 1,2-đimetylxiclopropan (8); 1,1-đimetylxiclopropan(9), etylxiclopropan (10)

- 5 đp mạch hở: CH2=CH-CH2-CH2-CH3, CH3-CH=CH-CH2-CH3, CH2=C(CH3)-CH2-CH3, CH3-CH(CH3)=CH-CH3, CH3-CH(CH3)-CH=CH2.

- 6 đp anken