During an inelastic collision between two objects,which of the following quantities always remains conserved?

$A$ ball of mass $1.2 \ kg$ moving with a velocity of $12 \ ms^{-1}$ makes a one-dimensional collision with another stationary ball of mass $1.2 \ kg$. If the coefficient of restitution is $\frac{1}{\sqrt{2}}$,then the ratio of the total kinetic energy of the balls after the collision to the initial kinetic energy is:

$A$ ball falls freely from a height $h$ on a rigid horizontal plane. If the coefficient of restitution is $e$,then the total distance travelled by the ball before hitting the plane the second time is

$A$ ball hits the floor and rebounds after an inelastic collision. In this case:

In an inelastic collision,after collision the kinetic energy

$A$ ball hits the floor and rebounds after an inelastic collision. In this case: