Answer: The v/v in percent of diethyl ether in a solution is 2%.
Step-by-step explanation:
To calculate the percentage volume by volume of a solute in a solution, we use the formula:

We are given:
Volume of solute = 50 mL
Volume of solution = 2.5 L = 2500 mL (Conversion factor: 1 L = 1000 mL)
Putting values in above equation, we get:

Hence, the v/v in percent of diethyl ether in a solution is 2%.