Provide definitions and explanations for the following terms:
$(i)$ Pollution
$(ii)$ Greenhouse effect

(N/A) $(i)$ Pollution: Pollution is defined as any undesirable change in the physical,chemical,or biological characteristics of air,land,water,or soil that adversely affects human life,industrial progress,living conditions,and cultural assets.
$(ii)$ Greenhouse effect: The greenhouse effect is a naturally occurring phenomenon that is responsible for heating of the Earth's surface and atmosphere. Without the greenhouse effect,the average temperature at the surface of the Earth would have been $-18^{\circ}C$ rather than the present average of $15^{\circ}C$.