If an element is a reactant or product in a chemical reaction, the reaction must be an oxidaton-reduction reaction. why is this true?

Explanation:

Oxidation reduction reactions are the reactions in which one specie oxidizes and other reduces.

For example,

This is a oxidation reduction reaction because sodium in elemental state ( 0 oxidation state) oxidizes to Na⁺ in NaCl. Also H⁺ in HCl reduces to H° in H₂.

Elements are present in 0 oxidation state and either it is formed or consumed, its oxidation state has to be changed for a chemical reaction to occur. Hence, it is true.

you need to take a look at the periodic system in order to sort these elements into pairs that would most likely exhibit similar chemical properties. first, you need to find elements that are found in the same group (groups are vertical in the periodic system), and then to see whether they have the same valence number. if they meet these criteria, they will have similar properties.

the first pair: ne (neon) and kr (krypton), are noble gases found in group 8

the second pair: li (lithium) and k (potassium), found in group 1

the third pair: s (sulfur) and te (tellurium), found in group 6

plasma is the state of matter where the substance is ionized and has no definite shape or volume. the fact of being ionized makes the substance a good electrical conductor.