All snakes are trees. Some trees are roads. All roads are mountains. Conclusions: 1. Some mountains are snakes 2. Some roads are snakes 3. Some mountains are trees

All snakes are trees. Some trees are roads.

Since the middle term is not distributed even once in the premises,so no conclusion follows

Some trees are roads. All roads are mountains

Since one primise is particular,the conclusion must be particularand should'nt contain the middle term. So,it follows that 'Some trees are mountains'. 3 is the converse of this statement and so it holds.

All snakes are trees. Some trees are mountains.

Since the middle term is not distributed even once in the preises, so no definite conclusion follows