Please solve 31,32,33,34

31. Four particles each of mass 'm' are placed at the corners of a square of side length 'l'. The radius of gyration of the system about an axis perpendicular to the plane of square and passing through its centre is
$$\begin{gathered} \left(1\right) \frac{l}{\sqrt{2}} \\ \left(2\right) \frac{l}{2} \\ \left(3\right) l \\ \left(4\right) \sqrt{2}l \end{gathered}$$

32. In the above problem the moment of inertia of four bodies about an axis perpendicular to the plane of frame and passing through a corner is
$$\begin{gathered} \left(1\right) {\mathrm{ML}}^2 \\ \left(2\right) 2{\mathrm{ML}}^2 \\ \left(3\right) 2\sqrt{2}{\mathrm{ML}}^2 \\ \left(4\right) 4{\mathrm{ML}}^2 \end{gathered}$$

33. In above problem the moment of inertia of four bodies about an axis passing through opposite corners of frame is
$$\begin{gathered} \left(1\right) \sqrt{2}{\mathrm{ML}}^2 \\ \left(2\right) 2{\mathrm{ML}}^2 \\ \left(3\right) {\mathrm{ML}}^2 \\ \left(4\right) 2\sqrt{2}{\mathrm{ML}}^2 \end{gathered}$$

34. In the above problem the moment of inertia of four bodies about an axis passing through any side of frame is 
$$\begin{gathered} \left(1\right) 4{\mathrm{ML}}^2 \\ \left(2\right) 2\sqrt{2}{\mathrm{ML}}^2 \\ \left(3\right) 2{\mathrm{ML}}^2 \\ \left(4\right) \sqrt{2}{\mathrm{ML}}^2 \end{gathered}$$