The nucleus of a atom contains the protons and the neutrons all most all of the atoms mass is weigh by the protons and the neurons.
Molar mass NaOH =23+16+1=40 g/mol
<span> 0.100 M= 0.100 mol/L
</span>500 ml=0.500 L
0.500L*0.100 mol/L=0.0500 mol NaOH we need to prepare 500 ml solution
0.0500 mol NaOH*40g/1mol=2 g NaOH we need to prepare 500 ml solution
we need 2 g NaOH, dissolve it in small amount of water, and dilute it with water up to 500 mL