It is either concave lens or mirror but since this is reflecting out rather than reflecting back it has to be concave lens. hope that helps! :’)
Potassium chloride reacts with ammonium nitrate to give ammonium chloride and potassium nitrate.
This is a type of double displacement reaction. The balanced chemical equation can be represented as,

Total ionic equation for this reaction will be,

There is no apparent reaction as this reaction is not accompanied by the formation of a gas or a solid precipitate. We cannot observe any visual reaction as there is not net reaction taking place. All the ions remain as spectator ions.
Just use q=mCDeltaT
q=energy
m=mass
c=specific heat
Delta T= Change in temperature