The mass of a planet is twice and its radius is three times that of earth then the weight of a body which has a mass of 5 kg on that planet will be

Acceleration due to gravity on the earth is given as:

$g_E=\frac{GM}{R^2}=9.8{\text{m/s}}^{\text{2}}$
Acceleration due to gravity on the planet will be:

$\begin{array}{c}{g}_P=\frac{G\cdot M_P}{R_P{ }^2}\because M_P=2M_E=2M\\ R_P=3R_E=3R\end{array}$
Substituting the values,

$g_P=\frac{G\times 2M}{{\left(3R\right)}^2}=\frac{2}{9}\frac{GM}{R^2}=\frac{2}{9}g$

A weight of 5 kg on the surface of the planet is given by:

$W_P=m\times g_P$

$W_p=5\times \frac{2}{9}g=\frac{10}{9}\times 9.8$

$W_P\Rightarrow 10.88N$