b
(b) \(\cdot\) Ratio of distance of two planets from sun \(\left(\frac{a_{1}}{a_{2}}\right)=1.38\)

\(\cdot\) Ratio of the period of revolution around sun is \(\left(\frac{T_{1}}{T_{2}}\right)=?\)

\(\Longrightarrow \frac{T_{1}}{T_{2}}=\frac{a_{1}}{a_{2}}^{3 / 2}\)

\(\frac{a_{1}}{a_{2}}=1.38(\text {Given})\)

\(\mathrm{So}\)

\(\Longrightarrow \frac{T_{1}}{T_{2}}=(1.38)^{3 / 2}\)

\(\frac{T_{1}}{T_{2}}=(1.38)^{3 / 2}\)