The value of acceleration due to gravity on the earth is maximum at which of the following?

The correct answer is B, the poles. The earth is flattened at the poles, so the distance from the centre is least there, and since g varies inversely as the square of that distance, g is largest at the poles. The rotation of the earth also reduces the effective value of g, and that reduction is greatest at the equator and zero at the poles, which adds to the difference.

Option A, the equator, is where g has its smallest surface value, for exactly the opposite reasons. Option C, the centre of the earth, is where g becomes zero, since the mass of the earth then surrounds the body on all sides and its pulls cancel out; a body there has weight zero although its mass is unchanged. Option D, the top of Mount Everest, is far above sea level, and g decreases with height, so it is smaller there than at sea level. The order worth remembering is poles greatest, equator smaller, height smaller still, centre zero.