# Solution "X" contains $Na_2 CO_3$ and $NaHCO_3.\;20 \;ml$ of $X$ when titrated using methyl orange indicator consumed $60\; ml$ of $0.1\;M\;HCl$ solution. In another experiment, $20 \;ml$ of X solution when titrated using phenolphthalein consumed $20\;ml$ of $0.1\;M\;HCl$ solution. The concentration (in mol $lit^{-1}$) of $Na_2CO_3$ and $NaHCO_3$ in X are respectively.
$(a)\;0.01,0.02 \quad (b)\;0.1,0.1 \quad (c)\;0.01,0.01 \quad (d)\;0.1,0.01$