Answer:
C
Explanation:
Chemical formulas are used to describe the types of atoms and their numbers in an element or compound. The atoms of each element are represented by one or two different letters. When more than one atom of a specific element is found in a molecule, a subscript is used to indicate this in the chemical formula.
Cl2 is the answer because we are asked to find the chemical formulae of an element where as the rest H20,NaCl,NH3 are compounds(formed by the bonding of two or more chemical elements ). where as Cl2 is formed by the polar bonds between Cl and Cl atoms hence Cl2 is the chemical formulae of the element chlorine since it exists in that form not as Cl.
