Цепочка 1) ch3-ch2-ch-ch3 + br2(свет) => x1 | ch3 2) x1 + koh => x2 3) x2 + hbr => x1 4) x1 + na => x3 5) x3 => co2

Объяснение:

1) H₃C-CH₂-CH(CH₃)-CH₃ + Br₂ =(hv)=> H₃C-CH₂-C(Br)(CH₃)-CH₃ (X1) + HBr;

2) H₃C-CH₂-C(Br)(CH₃)-CH₃ + KOH (вод. р-р) => H₃C-CH₂-C(OH)(CH₃)-CH₃ (X2) + KBr;

3) H₃C-CH₂-C(OH)(CH₃)-CH₃ + HBr => H₃C-CH₂-C(Br)(CH₃)-CH₃ (X1) + H₂O;

4) H₃C-CH₂-C(Br)(CH₃)-CH₃ + 2Na => H₃C-CH₂-C(CH₃)₂-C(CH₃)₂-CH₂-CH₃ (X3) + 2NaBr;

5) 2H₃C-CH₂-C(CH₃)₂-C(CH₃)₂-CH₂-CH₃ + 31O₂ => 20CO₂ + 22H₂O.