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.

vanderwaal's forces of attraction are the electrostatic intermolecular forces that exist in a molecule due to the temporary or permanent dipoles that are developed in a molecule. in , the major intermolecular forces are dipole-dipole interactions as the molecule is polar (bent structure). so the vanderwaal's forces of interaction in between molecules are the permanent dipole-dipole interactions that develop due to the dipole that exists in between the polar h - s bond. the positively charged hydrogen atom is attracted towards the negative end of the dipole that is sulfur of the adjacent molecule. therefore, these forces of attraction are relatively stronger than that of london dispersion forces that exist in non polar molecules.

i think that the answer is c