Answer: 3.85%
Explanation: To calculate the volume percentage of ethanol in the mixture, we need to determine the total volume of the mixture first.
Total volume = volume of ethanol + volume of water
Total volume = 10 ml + 250 ml
Total volume = 260 ml
Now, we can calculate the volume percentage of ethanol in the mixture using the following formula:
Volume percentage of ethanol = (volume of ethanol ÷ total volume) x 100%
Plugging in the values, we get:
Volume percentage of ethanol = (10 ml ÷ 260 ml) x 100%
Volume percentage of ethanol = 3.85%
Therefore, the volume percentage of ethanol in the mixture is 3.85%.