Mechanical Properties of Fluids — Physics STD 11 Science — Question

2. High viscosity.
3. Low density.

Explanation:

Streamline flow is more likely for liquids having low density. We know that greater the coefficient of viscosity of a liquid more will be the velocity gradient, hence each line of flow can be easily differentiated. Streamline flow is related with critical velocity. The critical velocity is that velocity of liquid flow up to which its flow is streamlined and above which its flow becomes turbulent.

As the critical velocity is related to viscosity $(\eta)$ and density $(\rho)$ of the liquid as,

$(\text{V}_\text{c})\ \alpha\ \frac{\eta}{\rho}$

Hence if the density will be low and viscosity will be high, the value of critical velocity will be more.