What do you understand by exothermic and endothermic reactions ? Describe an exothermic reaction.

In exothermic reaction

For an exothermic reaction

(a) What do you understned by exothermic and endothermic reactions ? (b) Give one example of an exothermic reaction and one of an endothermic reaction. (c ) Which of the following are endothermic reactions and which are exothermic reactions ? {:((i),"Burning of natural gas",(ii),"Photosynthesis"),((iii),"Electrolysis of water",(iv),"Respiration"),((v),"Decomposition of calcium carbonate",,):}

What does one mean by exothermic and endothermic reactions? Give examples