1.
Đặt $n_{CH_4}=n_{C_2H_4}=x (mol)$
$CH_4+2O_2\buildrel{{t^o}}\over\to CO_2+2H_2O$
$C_2H_4+3O_2\buildrel{{t^o}}\over\to 2CO_2+2H_2O$
$\Rightarrow n_{CO_2}=n_{CH_4}+2n_{C_2H_4}=3x (mol)$
$CO_2+Ca(OH)_2\to CaCO_3+H_2O$
$n_{CaCO_3\downarrow}=\dfrac{3}{100}=0,03(mol)$
$\Rightarrow 3x=0,03$
$\Leftrightarrow x=0,01$
$\to V=22,4(x+x)=0,448l$
2.
$C_2H_2+2Br_2\to C_2H_2Br_4$
$\Delta m=2,6g=m_{C_2H_2}$
$\Rightarrow n_{C_2H_2}=\dfrac{2,6}{26}=0,1(mol)$
$V_{C_2H_2}=0,1.22,4=2,24l$
$\to \%V_{C_2H_2}=\dfrac{2,24.100}{6,72}=33,33\%$
$\to \%V_{CH_4}=66,67\%$