Final answer:
The measurement 0.2503 L has four significant figures, which include one zero that is between non-zero digits and therefore counts as significant.
Step-by-step explanation:
The measurement 0.2503 L contains four significant figures. In significant figure rules, all non-zero digits are always significant, and any zeros between them are also significant. Therefore, starting with the first non-zero digit, count all the digits including the zero; in this case, that would be 2, 5, 0, and 3, making the total four significant figures.