Answer
$11.98\;s$
Work Step by Step
$|\tau|=k|\theta|$
Substituting given values
$k=\frac{0.20}{0.85}\;N/rad$
Therefore, the period of the oscillations of the solid sphere is given by
$T=2\pi\sqrt {\frac{I}{k}}$
or, $T=2\pi\sqrt {\frac{2MR^2}{5k}}$
or, $T=2\pi\sqrt {\frac{2\times95\times0.15^2\times0.85}{5\times0.20}}$
or, $T=11.98\;s$
