Why can astronauts jump higher on the surface of the moon than on the surface of the earth? Is it because their legs are stronger? Has the amount of "body matter," i.e., "mass" changed? Do they weigh less on the moon than on earth? Why

Answer 1

No, the mass does not change.

Yes, they weigh less on the moon; because g is 9.8 on earth but only 1.63
on the moon.