Câu 1:
(1) $2CH_4\xrightarrow{{1500^oC}} C_2H_2+3H_2$
(2) $C_2H_2+H_2\xrightarrow{{Pd/PbCO_3, t^o}} C_2H_4$
(3) $C_2H_4+Br_2\to BrCH_2-CH_2Br$
Câu 2:
$CH_2=CH-CH_3+Br_2\to CH_2Br-CHBr-CH_3$
Propan không phản ứng nên khí bay ra lad propan.
$\%V_{C_3H_8}=\dfrac{1,8.100}{2,4}=75\%$