Logical deduction – "all that flows have viscosity": Choose the correct implication or contrapositive pair. (i) It flows. (ii) It does not flow. (iii) It has viscosity. (iv) It does not have viscosity.

Introduction / Context:
"All that flows have viscosity" is Flows ⇒ HasViscosity. The logically equivalent contrapositive is NotHasViscosity ⇒ NotFlows.

Given Data / Assumptions:

• If something flows, it must have viscosity.
• If it lacks viscosity, it cannot flow.

Concept / Approach:
Option (iv) (ii) states the contrapositive pair: not having viscosity implies not flowing.

Step-by-Step Solution:

Verification / Alternative check:
(iii) (i) incorrectly assumes HasViscosity ⇒ Flows (converse). Many solids have viscosity-defined properties but do not "flow" macroscopically.

Why Other Options Are Wrong:
(iii) (i) is converse fallacy. (c) is meaningless as written. (d) is false.

Common Pitfalls:
Reversing subset implications.

Final Answer:
(iv) (ii)