Răspuns:
alchena are formula moleculara CnH2n, deci C4H8 si C5H10
CH2=CH-CH2-CH3 1 butena
CH2=C(CH3)-CH3 2 metil propena
CH2=CH-CH2-CH2-CH3 1 pentena
CH3-CH=CH-CH2-CH3 2 pentena
CH2=C(CH3)-CH2-CH3 2metil 1 butena
CH2=CH-C(CH3)-CH3 3 metil 1 butena
CH3-C(CH3)=CH-CH2 3metil 2 butena
Explicație: