Question

Is force of attraction between body and earth equal to gravitational force if body weighs 30 kg on earth.

Answer 1

No matter what the mass of the body, the gravitational force of attraction betweeen the body and the earth is equal to the wight og the body on earth. Here is the proof,
$F=\frac{GMm}{R^2}=\frac{GM}{R^2}\times m=g\times m=mg=W$
W is the weight of the body.