\(CO_2+Ca\left(OH\right)_2\rightarrow CaCO_3\downarrow+H_2O\)
Tl1............1.................1................1.(mol)
Br0,4...........................0,4....................(mol)
\(n_{CO_2}=\dfrac{9,916}{24,79}=0,4\left(mol\right)\)
\(\Rightarrow m_{CaCO_3}=n.M=0,4.100=40\left(g\right)\)