Performing and observing the following
reactions and classifying them into:
A.
Combination reaction
B.
Decomposition reaction
C.
Displacement reaction
D.
Double displacement reaction
(i)
Action of water on quicklime
(ii)
Action of heat on ferrous sulphate crystals
(iii)
Iron nails kept in copper
sulphate solution
(iv)
Reaction between sodium sulphate and barium chloride solutions

Dear student,

A) Quick lime is calcium oxide (CaO). When water is added to a small quantity of quick lime in a beaker, it forms a suspension of slaked lime (Ca(OH)₂). The beaker becomes hot as the reaction is exothermic. It is a combination reaction.
$CaO + H_{2}O \to Ca(OH{)}_2$

B) Take ferrous sulphate crystals in a dry boiling tube and hold the tube with a tube holder. On heating, the colour of crystals changes from green to white and then brown and a gas with the smell of burning sulphur is evolved. It is a decomposition reaction.
$$\begin{gathered} 2FeS{O}_4. 7H_{2}O \underset{ -14H_{2}O}{\overset{∆}{\to }} 2FeS{O}_4 \stackrel{∆}{\to } F{e}_2{O}_{3 }+ S{O}_2\left(g\right)+ S{O}_3\left(g\right) \\ Green white brown \end{gathered}$$

C)Iron being more reactive than copper will displace copper from copper sulphate solution. A brown layer of copper will be deposited on iron nail and blue colour of the solution will fade away. It is a displacement reaction.
$Fe + CuS{O}_4 \to FeS{O}_4 + Cu$

D) On mixing a solution of barium chloride with sodium sulphate, a white precipitate of barium sulphate is formed. It is a double displacement reaction. 
$$\begin{gathered} BaC{l}_2 + N{a}_{2}S{O}_4 \to BaS{O}_4 + 2NaCl \\ Barium sodium barium sodium \\ chloride sulphate sulphate chloride \end{gathered}$$



Regards