Why do convection currents form

Convection currents can happen in liquids and gases. For example when air is heated it becomes less dense and rises. This means that cooler more dense air comes down and is also heated rising up above more cooler air etc. This creates a convection current.
Here is a diagram of a hot water tank heater:
(sorry it isn't that great I did it myself just now)

If you open the bottle of perfume then nothing but the smell will come out of it and yes it is a type of gas smell because it’s say it in english so i can understand better and you

Answer it is also known as the completion state is untrue of the activation complex;