Explanation:

Compound A reacts with water and GIVES compound B which is used in whitewashing.

Compound A + water → Compound B (used in white washing)

The substance used for white washing is CaO (Calcium Oxide).

Therefore, compound A is Calcium oxide having formula CaO.

\sf{CaO+H_2O\rightarrow Ca(OH)_2}CaO+H

2

O→Ca(OH)

2

So, compound B is Calcium Hydroxide (another name - Slaked lime) having formula Ca(OH)2.

The above reaction is an example of a Combination Reaction. Because in it two or more reactants combine to form a single product.

Now, compound B reacts with carbon DIOXIDE to form a white precipitate of compound C.

Compound B + Carbon dioxide → Compound C (which forms white precipitate)

\sf{Ca(OH)_2+CO_2\rightarrow CaCO_3+H_2O}Ca(OH)

2

+CO

2

→CaCO

3

+H

2

O

Therefore, compound C is Calcium Carbonate.

The above reaction is an example of a DOUBLE Displacement Reaction. Because the exchange of ions takes PLACE. Also, known as PRECIPITATION Reaction, as the formation of precipitate takes place.