(i) Solid calcium oxide was taken in a container and water was added slowly to it :
(a) Write the observation.
(b) Write the chemical formula of the product formed.
(ii) What happens when carbon dioxide gas is bubbled through lime water :
(a) in small amount (b) in excess.

Explanation

(i) (a) A white suspension would be formed. Since the chemical reaction is highly exothermic in nature, the bubbles would appear accompanied by hissing sound.
(b) `CaO(s) + H_(2)O(aq) to underset("(White suspension)")(Ca(OH)_(2)(s) +) "heat"`.
(ii) (a) Lime water intially becomes milky due to the formation of calcium carbonate.
`{:(Ca(OH)_(2)(s) + CO_(2)(g) to, CaCO_(3)(s) + H_(2)O (l)),("(Lime water)", "(Milky)"):}`
(b) Upon bubbling the gas in excess, the white milkiness disappears due to the formation of water soluble calcium hdyrogen carbonate.
`CaCO_(3)(s) + CO_(2)(g) + H_(2)O(aq) to underset("(Water soluble)")(Ca(HCO_(3))_(2))(aq)`