In the question two statements are given, followed by two conclusions, I and II. You have to consider the statements to be true even if it seems to be at variance from commonly known facts. You have to decide which of the given conclusions, if any, follows from the given statements.
Statement I: Some phones are devices
Statement II: All mobiles are phones

Conclusion I: All devices are mobiles
Conclusion II: No mobiles are devices

Let's analyze the statements using Venn diagrams or logical relations:
Statement I: Some phones are devices (Overlap exists between Phones and Devices).

Statement II: All mobiles are phones (The entire set of Mobiles lies inside the set of Phones).

Now let's verify the conclusions:

Conclusion I: All devices are mobiles → There is no direct link given confirming all devices are inside mobiles. Thus, this is not definitely true. (Does not follow)

Conclusion II: No mobiles are devices → Since mobiles are inside phones, and some phones are devices, it is possible for mobiles and devices to overlap. A strict negative relation "No mobiles are devices" cannot be definitely concluded. (Does not follow)

Therefore, neither conclusion I nor conclusion II follows.