Assertion A: Product of Pressure (P) and time (t) has the same...

Viscous force is given by $F = ηA\left(\dfrac{d v}{d t}\right)$, here, $A$ is area and $\dfrac{d v}{d t}$ is velocity gradient.

Thus, $η = \dfrac{F}{A\left(\dfrac{d v}{d t}\right)}$.

Now, $Pt = \dfrac{F}{A}t = η\left(\dfrac{d v}{d t}\right)t$

Then, \left[Pt\right] = M{L}^{- 1}{T}^{- 1} = \left[η\right]

Thus, assertion is true but reason is false.