What does it mean by solution in salt solution, sugar solution, etc.

Sugar and salt and substances that easily gets dissolved inside the water as they are soluble in water and form solutions of sugar solution and salt solution. Salt and sugar are homogeneous mixture because any substance that is dissolve in water is a homogeneous mixture

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.

the answer is na (sodium)