\(n_{CH_4}=\dfrac{5.6}{22.4}=0.25\left(mol\right)\)
\(CH_4+2O_2\underrightarrow{^{t^0}}CO_2+2H_2O\)
\(0.25................0.25\)
\(Ca\left(OH\right)_2+CO_2\rightarrow CaCO_3+H_2O\)
\(..............0.25......0.25\)
\(m_{CaCO_3}=0.25\cdot100=25\left(g\right)\)