Answer: the theory that all matter us made up of tiny invisible particles. Hope that help you out :)
Explanation:
The answer is A.
Pure substance is either an element or a compound, which elements in compund is chemically combined together. They cannot be separated by physical methods such as filtration or evaporation. Compounds can only be separated by chemical methods, which include using electricity (electrolysis) or applying heat.
Answer: Krypton
Explanation:
7(14)=84
Krypton, if you look at the periodic table, has an atomic mass of approximately 84. It has a large nucleus, so while it is stable (due to its full octet) the nucleus is probably unstable due to repulsive forces between protons in the nucleus so is probably radioactive.
At the same time there is increased usage of chlorofluorocarbon [CFC].
CFC are halogenated compounds which have ability to destroy the ozone layer. When ultraviolet ray strike CFC in the atmosphere, it breaks the forces holding the molecule together and yield a chlorine atom. The chlorine atom then react with the ozone layer, breaking it apart and destroying it.<span />
