Answer : The correct option is, Subscript numbers tell us how many of the element to their upper-left there are in the molecule.
Explanation :
Subscript number : It indicates that the total number of atoms of an element present in a molecule.
While witting a chemical formula, first we have to write the symbol of an element and then write the number in the bottom of the symbol.
For example :
[tex]C_6H_{12}O_6[/tex] is the chemical formula of the glucose molecule. The glucose molecule is made up of six carbon atoms, twelve hydrogen atoms and 6 oxygen atoms.
The number 6 of carbon atom is written after and in the bottom (lower-right) of the symbol of carbon element (C). Similarly, the number 12 is written lower-right of the symbol of hydrogen element (H) and the number 6 is written lower-right of the symbol of oxygen element (O).
Therefore, the subscript numbers tell us how many of the element to their upper-left there are in the molecule.