Question

Where is the value of gravitation on earth is zero?

Answer 1

Here is your answer

The value of acceleration due to gravity is 0 at the centre of earth

Actually, maximum value of g is at surface of earth i.e. 9.8m/s^2

As we move up or down from the earth's surface the value of g decreases because
g= GM/r^2
where G is gravitational constant, M is mass of earth and r is radius of earth

So, g is inversely proportional to square of radius of earth
When radius is zero (at the center of earth) then g also becomes zero

Hope it is useful