Respuesta :

Volume  = 26.5 mL / 1000 => 0.0265 L

Molarity = 0.500 M

n = M x V

n = 0.500 x 0.0265

n = 0.01325 moles 

hope this helps!
0,5 M means that there are 0,5 moles of NaOH in 1 000 mL of solution:

[tex]26,5\ mL\cdot \frac{0,5\ mol}{1\ 000\ mL} = \bf 1,32\cdot 10^{-2}\ mol[/tex]