What is the rest and motion?​

A body is said to be at rest of it does not change its position with respect to a fixed point taken as a reference point in its surroundings, with the passage of time.

A body is said to be in motion if it's changes its position continuously with respect to a fixed point, taken as a reference point in its surroundings, with the passage of time.

explanation:

0.07 g/cm³

1.37 g/cm³

the answer is a! (2.9 x 10^-18 j) hope i could someone. : )