Write the chemical equation of the reaction with an example each in which the following change has taken place: (i) Change in colour (ii) Change in temperature (iii) Formation of precipitate.

Write the chemical equation of the reaction with an example each in wh

1.	Write the chemical equation of the reaction with an example each in which the following change has taken place: (i) Change in colour (ii) Change in temperature (iii) Formation of precipitate.
Answer» SOLUTION :(i) Change in colour : Reaction between lead nitrate solution and potassium iodide solution. `Pb(NO_(3))_(2)(aq)+2KIrarrPbI_(2)(S)+2KNO_(3)(aq)` In this reaction, colour changes from colourles to yellow. (ii) Change in temperature : ACTION of DILUTE sulphuric acid on zinc. `Zn(S)+H_(2)SO_(4)(aq)rarrZnSO_(4)(aq)+H_(2)` In this reaction, heat is evolved (iii) Formation of precipitate : Action of barium CHLORIDE on SODIUM sulphate . `BaCl_(2)(aq)+Na_(2)SO_(4)(aq)rarrBaSO_(4)(S)+2NaCl(aq)(ppt.)`