1. a. Yellow Colour precipitate of Lead Iodide is formed
b. It is nothing but Lead Iodide
c. 2KI (aq) + Pb(NO3)2 (aq) ---------> PbI2 (gas) + 2KNO3 (aq)
d. It is Chemical double Displacement Reaction.
2. Ca(OH)2 + HNO3 --> Ca(NO3)2 + H2O
OH2 on left and 1 on right side - put a 2 in front of H2O
Then the reaction will be,
Ca(OH)2 + HNO3 --> Ca(NO3)2 + 2H2O
Ca is balanced on both sides.
H is not balanced on both sides
So, keep 2 in front of HNO3
Then the reaction will be
Ca(OH)2 + 2HNO3 --> Ca(NO3)2 + 2H2O
2 NO3 is balanced on both sides
Hence the equation is balanced
therefore the balanced equation is:
Ca(OH)2 + 2 HNO3 --> Ca(NO3)2 + 2 H2O
3. The colour of copper sulphate solution change when an iron nail is dipped in it. Because Iron is more reactive than copper. We know that the more reactive elements are displaced to the position of less reactive ones. So due to the reaction that takes place here, the Iron nail turned into brownish colour and the copper sulphate colour gets fades.
4. when zinc granules are added to dil.sulphuric acid, a gas is evolved. It is nothing but Hydrogen.
the reaction occured here is shown in the form of equation.
Zn + H2SO4 -------------> ZnSO4 + H2 (gas)
hence, the gas evolved here is Hydrogen.