What is the force on a 1-kg ball that is falling freely due to the pull of gravity

Force = mass * acceleration, with units kg*m / second squared, or the more commonly the Newton, N. Assuming objects freely fall due to gravity at 9.8 m/second squared, and zero air resistance force opposing the freely falling object, 1 kg * 9.8 m/second squared = 9.8 N = force on the ball.

That force is called the "weight" of the ball. If it's anywhere on or near the Earth's surface, it's 9.8 Newton's (2.205 pounds). It makes no difference whether the ball is rising, falling, just laying there, rolling through air, or floating in chicken soup.