`A overset("Calcination")rarr CaO + MgO + underset("Colourless gas")((B))`  When th
Channel: Doubtnut
Date: 2020-07-26

`A overset("Calcination")rarr CaO + MgO + underset("Colourless gas")((B))`  When the colourless gas `(B)` is passed through lime water, initially a milky solution is obtained and on excess passage of gas `(B)` through the lime water, milkiness disappears.  `(A)` is :