Step 1: Understanding Hausner's ratio.
Hausner’s ratio is an empirical number that measures the flowability of powders. It is calculated as:
\[
\text{Hausner's ratio} = \frac{\text{Tapped density}}{\text{Bulk density}}
\]
A Hausner’s ratio between 1.50 and 1.61 indicates powders with fair passable flow, meaning the powders are somewhat cohesive but can still flow with moderate effort.
Step 2: Analyzing the options.
(1) Very poor flow: Incorrect, this range indicates fair passable flow, not very poor.
(2) Fair passable flow: Correct — This range of Hausner’s ratio corresponds to fair passable flow.
(3) Excellent flow: Incorrect, excellent flow is associated with a Hausner's ratio below 1.25.
(4) Very very poor flow: Incorrect, this is not accurate for the given Hausner’s ratio.
Step 3: Conclusion.
The correct answer is (2) Fair passable flow.