One end of a long iron chain of linear mass density  λ is fixed to a sphere of mass  m and specific density 1/3  while the other end is free. The sphere along with the chain is  immersed in a deep lake. If specific density of iron is 7, the height  h above the bed of the lake at which the sphere will float in equilibrium is xmλ.Find x. (Assume that the part of the chain lying on the bottom of the lake exerts negligible forces on the upper part of the chain)