# What mass of sodium hydroxide is needed to prepare 2.0L of 0.25mol L-1 of NaOH solution?

$\text{Option B}$
$2.0 \cdot L \times 0.25 \cdot m o l \cdot {L}^{-} 1 = 0.5 \cdot m o l$. Since we know that molar mass of sodium hydroxide is $40.0 \cdot g \cdot m o {l}^{-} 1$, we need a mass of $20 \cdot g$ of stuff.