Hi,

Steel is more elastic than rubber as in physics elasticity as a property is measured by young’s modulus(Y) the greater the value of ‘Y’ the material is more elastic.

Y=Stress/strain

here stress is proportional to applied force and strain is proportional to elongation of specimen.

now take two identical rods of steel and rubber and apply equal forces on their ends, now measure the elongation in them, obviously the elongation in rubber rod is much greater than that of steel rod. so the value of Y for Steel gets much larger than that for rubber, and so steel is more elastic than rubber.