Which of the following numerical statements serves as a counterexample to prove that $\sqrt{a - b} = \sqrt{a} - \sqrt{b}$ is NOT a valid general rule?

True or False: The sum of any two irrational numbers is always another irrational number.

True or False: For any two positive real numbers $a$ and $b$, the identity $\sqrt{a+b} = \sqrt{a} + \sqrt{b}$ is always true.

Simplify $\sqrt{72}$ to its simplest radical form.

Without using a calculator, determine which of the following values is the largest.