If r denotes a correlation coefficient, which of the following expressions is false

The fundamental property of the correlation coefficient $r$ is that its value must always be between $-1$ and 1, inclusive.

$$-1 \le r \le 1$$

This means that $r$ cannot be less than $-1$ and cannot be greater than 1.

To determine which specific expression is false, the list of expressions needs to be provided. However, any expression that states $r$ is outside the range of $[-1, 1]$ would be false. For example, an expression like $r = 1.2$ or $r = -1.5$ would be false. Similarly, an expression stating that $r^2 < 0$ would also be false, as $r^2$ must always be non-negative and between 0 and 1.