Consider the following statements : 

Statement-1: ${\mathrm{Cu}}^{2+}$ ions are reduced to ${\mathrm{Cu}}^{+}$ by potassium iodide and potassium cyanide both, when taken in excess. 

Statement-2: ${\mathrm{H}}_2\mathrm{S}$ will precipitate the sulphide of all the metals from the solutions of chlorides of Cu, Zn and Cd if the solution is aqueous. 

Statement-3: The presence of magnesium is confirmed in qualitative analysis by the formation of a white crystalline precipitate of ${\mathrm{MgNH}}_4{\mathrm{PO}}_4$ . 

Statement-4: Calomel on reaction with potassium iodide gives red precipitate.