**Reason:** The square roots of all positive integers are irrationals.
1. Assertion: 3 is a rational number because it can be expressed as the ratio of two integers (3/1). This statement is true.
2. Reason: The statement "The square roots of all positive integers are irrationals" is incorrect. While many square roots of positive integers are irrational (e.g., the square root of 2, the square root of 3, the square root of 5), the square roots of perfect squares are rational (e.g., the square root of 1 is 1, the square root of 4 is 2, the square root of 9 is 3). This statement is false.
