How is the mass of a liquid substance affected after it freezes a) it increases. b) it decreases. c) it stays the same.

 C) It stays the same.

Explanation: Suppose you have a kilogram of water in a closed container, now, if you freeze the water (inside the container) there is no way in which ani mass can enter in the mixture or get out. So the number of particles in the container can not change, this means that the mass does not change.

You actually can see a change in the volume (and also in the density) but the mass does not change, so the correct option is C.

0.19 m/s and 0.45 m/s

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.