The earth has Volume 'V' and surface area 'A' then its capacitance would be
If we assume shape of earth be solid spherical.
Then, the volume of earth=4/3πR3
where R is radius of earth.
Given, volume of earth=V=4/3πR3
surface area of earth=A=4πR2
So, V/A=(4/3R3)/4πR2
or V/A=R/3
or, R=3V/A
Now, capacitance of earth=4π∈0R
=4π∈03VA
=12π∈0VA.