Diffusion refers to the force of attraction between the particles of the same substance the force of attraction between the particles of two different substances the random movement of one substance through another separation of one substance from another based on differences in density

The correct option is ' random movement of one substance through another'.

Explanation:

Diffusion is defined as movement of the particles from area having higher concentration to the area having lower concentration. It is usually observed  in gases and liquids.

For example: Drop of ink in water

r just means there's a number of carbon in teh chain. for example rcooh means that after x number of carbon, the chain ends with cooh.

explanation:

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.