Why is sulphur more reactive than chlorine

Because the most reactive elements are HALOGENS.

Halogens are considered the most reactive elements. ... This property makes them more reactive. Chlorine reacts very strongly. It is considered more reactive than sulphur because chlorine loses one electron to complete its outer most shell while sulphur loses two electron which make it less reactive than chlorine.

a rain shadow is a dry region of land on the side that is protected against the prevailing winds of a mountain range. the prevailing winds are the winds that occur most of the time in a particular place of the earth

prevailing winds carry air toward the mountain range. as the air rises up over a mountain range, the air cools, water vapor condenses, and clouds form. on this side of the mountains, called the windward side, precipitation falls in the form of  rain  or snow. this dry air produces a  rain shadow.