The quantities remaining constant in colision are

The quantity remaining constant on dilution is

Which two physical quantities remains constant in law of conservation of momentum? Which quantity remain zero?

A steady current flow in a metallic conductor of non-uniform cross-section. The quantity/quantities remaining constant along the whole length of the conductor is /are.

Which of following quantities remains constant in transformer ?

Name the physical quantities which remain constant in a planetary motion (in elliptical orbits).