PLEASE PLEASE HURRY AND BE CLEAR!
If a substance has a half-life of one year, how long will it take for half of the substance to decay?

Based on their location in the atmosphere, the layers are able to have their own special characteristics. for example, most weather occurs in the troposphere. what occurs in each of the other layers?

Identify the type of chemical reaction involved in each action.

Japan is a group of four islands off the coast of asia. what effect do you think has had on the lives of the japanese?