If you wanted to prepare 500 mL of a 0.20M solution of dextrose (C6H12O6) in water, how much dextrose would you need?

18 g

Explanation:

The molar mass of dextrose is obtained as shown. Then the formula for number of moles is applied as shown in the image. Number of moles= mass/molar mass= concentration × volume. The volume is measured in dm3 hence the denominator of 1000. By making mass of solute the subject of the formula, we obtain the mass of dextrose requited to prepare the desired concentration of solution in the desired volume.

atomic mass = 39

number of neutrons = 20

number of protons= 19

electronic configuration = 1s2 2s2 2p6 3s2 3p6 4s1

the number of electron in first shell = 2

number of electrons in n=3 shell = 8

it is b that is the answer.