Which one of the following statements is not correct?

Statement 4 is incorrect because mass and weight are fundamentally different physical quantities with different units. Mass is the quantity of matter in an object, measured in kilograms (kg), and remains constant regardless of location [2]. Weight is the gravitational force exerted on an object, measured in Newtons (N), and varies based on the local gravitational field [4]. At sea level on Earth, a 1 kg mass weighs approximately 9.8 Newtons; thus, they are never numerically 'equal' in standard scientific units [4]. Statement 1 is correct as weight depends on a planet's gravity [1]. Statement 2 is correct because mass is an intrinsic property that does not change in space or on the moon [1]. Statement 3 is correct as weightlessness occurs during free-fall or when gravitational forces are counter-balanced, such as in orbit.

Sources

1. [1] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 5: Exploring Forces > A step further > p. 75
2. [2] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 9: The Amazing World of Solutes, Solvents, and Solutions > A step further > p. 142
3. [4] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 5: Exploring Forces > Snapshots > p. 77