\(n_{CO_2}=\dfrac{0.56}{22.4}=0.025\left(mol\right)\)
\(n_{KOH}=0.1\cdot0.6=0.06\left(mol\right)\)
\(2KOH+CO_2\rightarrow K_2CO_3+H_2O\)
\(0.05..........0.025.......0.025\)
\(m_{K_2CO_3}=0.025\cdot138=3.45\left(g\right)\)
\(C_{M_{KOH\left(dư\right)}}=\dfrac{0.01}{0.1}=0.1\left(M\right)\)
\(C_{M_{K_2CO_3}}=\dfrac{0.025}{0.1}=0.25\left(M\right)\)