copper sulphate solution turns the colour of litmus into red but litmus changes into blue with baking soda solution although both are salts. Give reason why?​

Copper sulphate is an acidic salt: It is the product of the reaction between a weak copper base and a strong acid , H2SO4

Litmus has a red colour in acidic solutions:

Conclusion: Acidic copper sulphate solution turns blue litmus to red

Baking soda is a basic salt : It is the reaction product of a weak acid , CO2 and a strong base , NaOH

Litmus has a blue colour in basic solutions:

Conclusion: basic baking soda solution turns red litmus to blue

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.