Question

describe how to identify a subscript in a chemical formula and its impact. it is before the element symbol and shows how many complete particles of a substance are needed it is the small number to the lower right of the element symbol and shows how many atoms of an element are present it is after the element symbol and shows how many complete particles of a substance are needed it is the large number to the lower left of the element symbol and shows how many atoms of an element are present

Explanation:

In a chemical formula, a subscript is the small number to the lower - right of an element symbol. It indicates the number of atoms of that element present in the molecule or compound. For example, in $H_2O$, the subscript 2 on $H$ means there are 2 hydrogen atoms.

Answer:

it is the small number to the lower right of the element symbol and shows how many atoms of an element are present