Four lead spheres a, b, c & d whose radii 1 cm, 2cm, 3cm, and 4cm respectively are dropped into liquids of coefficients of viscosity $1\times {10}^{-3} \mathrm{Pa}-\mathrm{s}, 2\times {10}^{-5 } \mathrm{Pa}-\mathrm{s} ,6.5\times {10}^{-3} \mathrm{Pa}-\mathrm{s}, 15.4\times {10}^{-3}\mathrm{Pa}-\mathrm{s}.$

Arrange the  spheres with their terminal velocity in descending order

Terminal velocity is calculated by ${\mathrm{V}}_{\mathrm{t}}=\frac{2{\mathrm{gr}}^2\left({\mathrm{\rho }}_{\mathrm{b}}-{\mathrm{\rho }}_{\mathrm{l}}\right)}{9\mathrm{\eta }}$

$\Rightarrow {\mathrm{V}}_{\mathrm{t}}\propto \frac{{\mathrm{r}}^2}{\mathrm{\eta }}$

For the above values, 

the four spheres' terminal velocities will be proportional to 

$\frac{1^2}{\left(1\times {10}^{-3}\right)},\frac{2^2}{\left(2\times {10}^{-5}\right)},\frac{3^2}{\left(6.5\times {10}^{-3}\right)},\frac{4^2}{\left(15.4\times {10}^{-3}\right)}$

which is 

$\left(1\times {10}^3\right), \left(2\times {10}^5\right), \left(1.38\times {10}^3\right), \left(1.038\times {10}^3\right)$

The terminal velocities are in the order of b, c, d, a.