$A$ $90 \,kg$ body placed at $2R$ distance from the surface of the Earth experiences a gravitational pull of: ($R=$ Radius of Earth,$g=10 \,ms^{-2}$) (in $\,N$)

Which of the following statements are true about acceleration due to gravity?
$(a)$ '$g$' decreases in moving away from the centre if $r > R$
$(b)$ '$g$' decreases in moving towards the centre if $r < R$
$(c)$ '$g$' is zero at the centre of the Earth
$(d)$ '$g$' decreases if the Earth stops rotating on its axis

The height at which the acceleration due to gravity becomes $\frac{g}{9}$ (where $g$ = the acceleration due to gravity on the surface of the earth) in terms of $R$,the radius of the earth,is

If the mass of Earth is $80$ times that of a planet and its diameter is double that of the planet,and $g$ on Earth is $9.8 \ m/s^2$,then the value of $g$ on that planet is ........ $m/s^2$.

The height at which the weight of the body becomes $\frac{1}{16}$ of its weight on the surface of the earth of radius $R$ is: (in $R$)

What will be the formula for the mass of the Earth in terms of $g$,$R$,and $G$?