Final answer:
The percent efficiency of the stove element is 25%.
Step-by-step explanation:
To find the percent efficiency of the stove element, we need to calculate the efficiency using the formula:
Efficiency = (useful output / input) x 100%
In this case, the useful output is the heat gained by the water, which is 5.00 x 10^2J, and the input is the heat supplied by the stove element, which is 2.00 x 10^3J.
Using the formula: Efficiency = (5.00 x 10^2J / 2.00 x 10^3J) x 100%
Simplifying, we get:
Efficiency = 25%