During inelastic collision between two bodies, which of the following quantities always remain conserved ?

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

In a perfectly inelastic collision between two bodies

In an elastic collision of two billiard balls which of the following quantities is not conserved during the short time of collision :

For inelastic collision between two spherical rigid bodies, which one of the following statements is correct?

Which of the following quantity is conserved in all collision prosess ?