Which of the following quantities has a unit but dimensionless?

Stokes' law states that the viscous drag force $F$ experienced by a sphere of radius $a$, moving with a speed $v$ through a fluid with coefficient of viscosity $\eta$, is given by $F=6 \pi \eta a v$.If this fluid is flowing through a cylindrical pipe of radius $r$, length $l$ and a pressure difference of $p$ across its two ends, then the volume of water $V$ which flows through the pipe in time $t$ can be written as

$\frac{v}{t}=k\left(\frac{p}{l}\right)^a \eta^b r^c$

where, $k$ is a dimensionless constant. Correct value of $a, b$ and $c$ are

The force $F$ is given in terms of time $t$ and displacement $x$ by the equation $F = A\,cos\,Bx + C\,sin\,Dt.$ The dimensional formulae of $D/B$ is

The $SI$ unit of a physical quantity is pascal-second. The dimensional formula of this quantity will be ..............

Which of the following is not a dimensionless quantity?

Dimensional formula of magnetic flux is