Four identical thin rods each of mass M and lengthl , form a square frame. Moment of inertia of this frame abut an axis through the centre of the square and perpendicular to its plane is

Moment of inertia of each rod about an axis through its centre and perpendicular to its length =M l212 Using theorem of parallel axes. M.I  of each rod about the given axis                =M l212+M(l2)2=M l23M.I  Of the square frame about the given axis=4 M l23 .