Number 1 I need help please

a. The chemical symbols represent the chemical element and are 1 to 2 letters long.

Example: Er- Erbium

b. The chemical formulas identify each element by it's chemical symbol and indicates the proportionate number of atoms in each element.

Example: Salt- NaCI

c. A chemical equation is the symbolic equation of a chemical reaction in the form of symbols and formulas.

Example: H2+O=H2O (One water molecule)

because u need two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei to form isotopes.

so since they all have the same shape? i mean maybe because m& m and reeses are both chocolates