How do you count atoms in a chemical formula?

To find out the number of atoms: MULTIPLY all the SUBSCRIPTS in the molecule by the COEFFICIENT

Explanation:

So, molarity is defined as the number of moles of solute per liter of solution. In your case, a 0.77 M solution will contain 0.77 moles of sodium chloride, your solute, in 1.0 L of solution.

Your target solution has a volume of

985mL⋅1 L103mL=0.985 L

which means that it will contain

0.985L solution⋅= 0.77 M0.77 moles NaCl1L solution=0.75845 moles NaCl

Sodium chloride has a molar mass of 58.44 g mol−1, which basically means that one mole of sodium chloride has a mass of 58.44 g.

In your case, 0.75845 moles of sodium chloride will have a mass of

0.75845moles NaCl⋅58.44 g1mole NaCl=∣∣ ∣∣¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯aa44 gaa∣∣−−−−−−−−

The answer is rounded to two sig figs, the number of sig figs you have for the molarity of the solution.