$A$ pure number which determines the type of flow of a liquid through a pipe is known as

The rate of steady volume flow of water through a capillary tube of length $l$ and radius $r$,under a pressure difference of $p$ is $V$. This tube is connected with another tube of the same length but half the radius,in series. Then,the rate of steady volume flow through them is (The pressure difference across the combination is $p$.)

When a liquid of density $\rho$ flows through a tube of diameter $d$ with critical velocity $V$,then the Reynolds number is (where $\eta$ is the coefficient of viscosity of the liquid).

Consider an increase of $1 \%$ in each of the radius of the artery,the viscosity of blood,and the density of blood,respectively. The percentage change in the flow rate of blood in the artery is (in $\%$)

What is critical speed in the context of fluid flow?

What will be the nature of flow of water from a circular tap,when its flow rate increases from $0.18\, L/min$ to $0.48\, L/min$? The radius of the tap is $0.5\, cm$ and the viscosity of water is $10^{-3}\, Pa\cdot s$. (Density of water: $10^{3}\, kg/m^{3}$)