Stream-line flow is more likely for liquids with

To determine the conditions under which a liquid exhibits stream-line (laminar) flow, we analyze the Reynolds number. The Reynolds number is a dimensionless quantity that helps predict flow patterns in different fluid flow situations.
The formula for the Reynolds number ($Re$) is given by:

$Re=\frac{\rho vd}{\eta }$

where:
• $\rho$ is the density of the liquid,
• $v$ is the velocity of flow,
• $d$ is the diameter of the tube, and
• $\eta$ is the coefficient of viscosity of the liquid.

For a flow to remain stream-line (laminar), the Reynolds number must be low (typically $Re<2000$). If the Reynolds number exceeds a critical value, the flow becomes turbulent.

From the formula, we see that to keep $Re$ as small as possible (which promotes stream-line flow):
1. The density ($\rho$) in the numerator should be low.
2. The viscosity ($\eta$) in the denominator should be high.

Therefore, stream-line flow is more likely for liquids with high viscosity and low density.

The correct answer is: High viscosity and low density