Question

HCOOH$\underset{Dehydrating Agent}{\overset{H_{2}S{O}_4}{→}}$CO + H₂O$\left(H_{2}O abosrbed by H_{2}S{O}_4\right)$
$$\begin{gathered} {\left(moles\right)}_i=\frac{2.3}{46}=\frac{1}{20}      0          0 \\ (moles{)}_f      0                      \frac{1}{20}      \frac{1}{20} \end{gathered}$$
H₂C₂O_{4$\stackrel{H_{2}S{O}_4}{→}$}CO+ CO₂+H₂O
[H₂O absorbed by H₂SO₄]
$(moles{)}_f        0         \frac{1}{20}     \frac{1}{20}       \frac{1}{20}$
CO₂ is absorbed by KOH.
So the remaning product is only CO.
moles of CO formed from both reactions
$=\frac{1}{20}+\frac{{\displaystyle 1}}{{\displaystyle 20}}=\frac{{\displaystyle 1}}{{\displaystyle 10}}$
Left mass of CO = moles × molar mass
$=\frac{{\displaystyle 1}}{{\displaystyle 10}}×28$
= 2.8 g Ans.