A star can be considered as a shpherical ball of hot gas of radius R.Inside the star the density of the gas is `rho_r` at a radius r and mass of the gas within this region is `M_r`.The correct differential equation for variation of mass with respect to radius `((dM_r)/(dt))` is (refer to the adjacent figure)

The value of mass and radius of sun are given by `M_0=2xx10^30` kg and `R_0=7xx10^5` km respectively.The pressure at the centre is about `(G=6.67xx10^(-11) m^3 kg^(-1) s^(-2))`.

Answer

`5xx10^14 N//m^2`