Please answer this question :

Dear Student,
Blade is made of iron.
When we dip blade in copper sulphate solution,
Thickness of blade decreases and eventually it disappeared and red coloured precipitate (Copper) is deposited at the bottom.  
The blue colour of solution disappears and solution becomes bluish-green
Temperature of solution increases because this process is exothermic i.e, heat is released.

CuSO₄ + Fe $\underset{}{\to }$ Cu + FeSO₄
(blue)                   (red)   (bluish green)

Regards