how many moles of sodium hydroxide are needed to prepare 250 ml of a 0.85 m solution?\na 0.0034\nb 3.4\nc…

Explanation:

Step1: Convert volume to liters

We know that $1L = 1000mL$. So, $V=250mL=\frac{250}{1000}L = 0.25L$.

Step2: Use molarity formula

The molarity formula is $M=\frac{n}{V}$, where $M$ is molarity, $n$ is the number of moles, and $V$ is volume in liters. Rearranging for $n$, we get $n = M\times V$. Given $M = 0.85M$ and $V=0.25L$, then $n=0.85\times0.25 = 0.2125\approx0.21$ moles.

Answer:

D. 0.21