a,
Gọi x, y là số mol $Na_2CO_3$, $CaCO_3$
$\Rightarrow 106x+100y=20,6$ (1)
$Na_2CO_3+2HCl\to 2NaCl+CO_2+H_2O$
$CaCO_3+2HCl\to CaCl_2+CO_2+H_2O$
$\Rightarrow 58,5.2x+111y=22,8$ (2)
(1)(2)$\Rightarrow x=y=0,1$
$\%m_{Na_2CO_3}=\dfrac{106x.100}{20,6}=51,5\%$
$\%m_{CaCO_3}=48,5\%$
b,
$n_{CO_2}=x+y=0,2 mol$
$\Rightarrow V=0,2.22,4=4,48l$
c,
$m_{dd B}=20,6+200-0,2.44=211,8g$
$C\%_{NaCl}=\dfrac{58,5.2x.100}{211,8}=5,5\%$
$C\%_{CaCl_2}=\dfrac{111y.100}{211,8}=5,24\%$