The gas thus evolved is CO2.
To find the nature of gas evolved,
1. CO2 has no color or smell.
2. In the presence of CO2 the burning splint will stop burning.
3. CO2 will turn moist litmus paper from blue to red, and moist universal indicator paper to yellow.
1.CO2 will tun lime water milky.
Lime water is the solution of calcium hydroxide.
Calcium Hydroxide + Carbon Dioxide= Calcium carbonate+ water
Ca(OH)(aq) + CO2(g) =CaCO3(s) +H2O(l)