V(HNO₃) = 50.0 mL in liters = 50.0 /1000 =0.05 L
M(HNO₃) = 1.50 M
Number of moles HNO₃ :
n = M x V
n = 1.50 x 0.05
n = 0.075 moles of HNO₃
HNO₃ + NaOH = H₂O + NaNO₃
1 mole HNO₃ -------- ---1 mole NaOH
0.075 moles HNO₃ ---- ?
moles NaOH = 0.075 * 1 / 1
= 0.075 moles of NaOH
V ( NaOH ) :
M = n / V
0.81 = 0.075 / V
V = 0.075 / 0.81
V = 0.0925 L or 92.5 mL
hope this helps!