Solution:
Since both the premises are particular, no definite conclusion follows. However, I and III involve only the extreme terms and form a complementary pair. So, either I or III follows. II is the converse of the first premise while IV is the converse of the second premise. Thus, both of them hold.

Solution:
No tree is fruit. All fruits are stones. Since the middle term 'fruits' is distributed twice, the conclusion must be particular. Since one premise is negative, the conclusion must be negative. So, it follows that 'Some stones are not trees'. All fruits are stones. All stones are rains. Clearly, it follows that 'All fruits are rains'. III is the converse of this conclusion and so it holds. No tree is fruit, All fruits are rains. As discussed above, the conclusion must be particular negative and should not contain the middle term. So, it follows that 'Some rains are not trees'. However, II and IV involve only the extreme terms and form a complementary pair. Thus, either II or IV follows.

Solution:
Since one premise is particular, the conclusion must be particular. So, neither I nor II follows.

Solution:
Since both the premises are universal and one premise is negative, the conclusion must be universal negative and should not contain the middle term. So, only I follows.

Solution:
All tigers are jungles. No jungle is bird. Since both the premises are universal and one premise is negative, the conclusion must be universal negative (E-type) and should not contain the middle term. So, it follows that 'No tiger is bird'. III is the converse of this conclusion and so it holds. No jungle is bird. Some birds are rains. Since one premise is particular and the other negative, the conclusion must be particular negative (O-type) and should not contain the middle term. So, it follows that 'Some jungles are not rains'. Since I and II also involve the same terms and form a complementary pair, so either I or II follows.

Solution:
Since each combination of premises has two particular premises, so no definite conclusion follows.

Solution:
All snakes are trees. Some trees are roads. Since the middle term is not distributed even once in the premises, so no definite conclusion follows. Some trees are roads. All roads are mountains. Since one premise is particular, the conclusion must be particular and should not contain the middle term. So, it follows that 'Some trees are mountains'. III is the converse of this conclusion and so it holds. All snakes are trees. Some trees are mountains. Since the middle term is not distributed even once in the premises, so no definite conclusion follows.