No, not all even numbers are perfect squares.
A perfect square is a number that can be expressed as the square of an integer. For example, the perfect squares less than 20 are 0, 1, 4, 9, and 16. Among these, 0, 4, and 16 are even numbers. However, not every even number is a perfect square.
For instance, the number 2 is an even number, but it cannot be expressed as the square of any integer, as there is no whole number that, when squared, results in 2. Similarly, other even numbers like 6, 8, 10, 12, and 14 are also not perfect squares.
In summary, while some even numbers are perfect squares (like 4 and 16), the majority of even numbers are not. Therefore, it is incorrect to say that all even numbers are perfect squares.