Answer: 0.16 M
Step-by-step explanation:
molarity is a way to measure the concentration of solutions, the equation is the amount of solute in mol / liter of solution:
mol (solute) / L (solution)
the first thing you want to do is convert grams to moles:
20g NaF • 1 mol
———— = 0.47632464 mol
41.98817 g (molar mass of NaF)
then you just want to follow with the rest of the equation:
0.47632464 mol NaF / 3.0 L = 0.15877488 or 0.16 M (sigfigs)
hope this helps :)