Answer: a compound is a substance that is made up of more than one type of atoms bonded together, mixtures are a mix of multiple elements or compounds which haven't bonded together.
Explanation:
Alkali metals impart characteristic colours to the flame due to low ionisation enthalpy, when an alkali metal or its salt is heated in a flame, the valence electrons are excited to higher energy level.
Answer:
I <em><u>THINK mechanical energy</u></em>
Answer: They are chemically stable gases
Explanation:
Group 18 is also called the noble gases - because they have full valence shells it means they are stable and won't chemically react.
