molar mass NaOH =23+16+1=40 g/mol
0.100 M= 0.100 mol/L
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
