In scientific notation, a number is correctly written when it is in the form \(a \times 10^n\), where \(a\) is a number greater than or equal to 1 and less than 10, and \(n\) is an integer.
Let’s evaluate the responses:
- 0.2520 × 10−3 - Not in proper scientific notation, as \(0.2520\) is less than 1.
- 25.20 × 103 - Not in proper scientific notation, as \(25.20\) is greater than 10.
- 10 × 103 - Not in proper scientific notation, as \(10\) is not less than 10.
- 2.520 × 103 - This is properly written in scientific notation, as \(2.520\) is between 1 and 10.
Thus, the correctly written number in scientific notation is 2.520 × 103.