Answer:
a
The potential of the earth surface is  [tex]V_E= - 9.6*10^9 V[/tex]
b
when the potential of the earth is zero the charge is choose to be negative this implies that  the potential at infinity would be [tex]V_\infty=+9.6*10^9V[/tex] and (Ignore the fact that positive charge in the ionosphere approximately cancels the Earth's net charge the potential at the surface increase and the electric field remains the same
Explanation:
From the question we are told that
   The magnitude  electric field is  [tex]E = 150V/m[/tex]
The potential of the earth surface when  V = 0 and  [tex]r = \infty[/tex] is mathematically represented as
        [tex]V_E = - \frac{q}{4 \pi \epsilon_o r} = - E *R[/tex] Â
Where q is the charge on the surface of the earth  which is negative
      R is the radius of the earth
      [tex]V_E = 150 * 64 *10^6[/tex]
         [tex]V_E= - 9.6*10^9 V[/tex]
when the potential of the earth is zero the charge is choose to be negative
Then the potential at infinity would be [tex]+9.6*10^9V[/tex]
