Assertion: When a piece of rock is brought from the moon to the earth, its mass changes. Reason (R) : The gravitational pull of earth is stronger than that of moon.

The assertion is false because mass is an intrinsic property of an object that represents the amount of matter it contains and remains constant regardless of location [c1, t7]. When a rock is moved from the moon to the earth, its mass does not change [c1, c3]. However, weight is the measure of the gravitational force acting on an object and varies based on the local gravitational field [c1, t7]. The reason is true because the Earth's gravitational pull is significantly stronger than that of the moon; specifically, the moon's gravitational acceleration is approximately 1.62 m/s², which is about one-sixth of Earth's 9.8 m/s² [t2, t3, t4]. Consequently, while the rock's mass remains invariant, its weight would increase upon being brought to Earth due to the stronger gravitational pull [c1, t1].

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 5: Exploring Forces > Prepare some questions based on your learnings so far ... > p. 78