Chapter 1 - Expressions, Equations, and Inequalities - 1-2 Properties of Real Numbers - Practice and Problem-Solving Exercises - Page 16: 61

Not true because the opposite of whole number 5 is -5, which is not a whole number.

This statement is only true for 0 and it is false for any other whole number. A whole number is all positive numbers, and 0. So the whole numbers would be ${0, 1, 2, 3, 4, 5, 6,...}$.