At the distance of 5 cm and 10 cm from surface of a uniformly charged solid sphere , the potentials are 100 V and 75 V respectively . Then which of the following statements are correct $\; $ 1. Potential at it's surface is 150 V $\;$2.The charge on the sphere is $\;\large\frac{50}{3}\;\times 10^{-10}\;C$ $\;$3.Electric field on the surface is $\;1500 V/m\;$ $\;$4.Electric potential it's centre is 25V $\;\quad \;$