If and S respectively denote the coefficient of viscosity and...

Dimensional formula for the coefficient of viscosity, $[\eta] = [M L^{-1} T^{-1}]$

Dimensional formula for surface tension, $[S] = \dfrac{\text{Force}}{\text{Length}} = \dfrac{[M L T^{-2}]}{[L]} = [M T^{-2}]$

Now, taking the ratio:
\left[\dfrac{\eta}{S}\right] = \dfrac{[M L^{-1} T^{-1}]}{[M T^{-2}]} = [M^0 L^{-1} T^1]$<br><br>Answer:$[M^0 L^{-1} T^1]