Syllogism — Mobiles, watches, and calculators (careful with middle term): Statements: (a) No mobile is a watch. (b) All watches are calculators. Conclusions to test: I. No calculator is a mobile. II. Some calculators are mobiles. Select what necessarily follows.

Introduction / Context:
This question tests whether you can avoid illicit conversions when a middle term changes grammatical role. “Watch” is the bridge between “mobile” and “calculator,” but we must not infer more than the premises license.

Given Data / Assumptions:

• No Mobile is a Watch (Mobile ∩ Watch = ∅).
• All Watch are Calculator (Watch ⊆ Calculator).
• No explicit existence of watches is stated.

Concept / Approach:
If there are watches, they fall inside calculators and are disjoint from mobiles. That says nothing about other calculators (non-watch calculators) possibly being or not being mobiles. Hence neither a universal negative (I) nor an existential positive (II) about the class Calculator vs Mobile is forced.

Step-by-Step Evaluation:
1) From (b), some calculators could be watches (if watches exist), and those are certainly not mobiles (by (a)).2) But calculators may also include devices that are not watches; the premises give no restriction on whether those could be mobiles.3) Therefore, “No calculator is a mobile” (I) is too strong, and “Some calculators are mobiles” (II) is not guaranteed.

Verification / Alternative check:
Model A: calculators = watches only → I would be true; Model B: calculators include some non-watch mobiles → II would be true. Since different models satisfy different conclusions, neither is necessary.

Common Pitfalls:
Confusing “All watches are calculators” with “All calculators are watches,” or assuming the existence of watches.

Final Answer:
Neither Conclusion I nor II follows.