Statements:
No guitar is a violin.
Some violins are pianos.
All sitars are pianos.
Conclusions:
I. Atleast some pianos are violins.
II. Some guitars are not pianos.
Some violins are pianos(I) ⇒ Conversion ⇒ Some pianos are violins(I). Hence, conclusion I follows. No guitar is a violin(E) + Some violins are pianos(I) ⇒ Some pianos are not guitars(O*). Hence, conclusion II does not follow.