Which numbers replace the question mark

Which will be the blank term in the following series?

h_eg_fegh_eghfe_

Twenty students are standing in a straight-line facing North. Rina is standing sixth from the left end. There are only three students between Rina and Shweta. Radha is standing exactly between Shweta and Rina. Tina is standing sixth to the right of Radha. Anita is standing fourth from the right end of the line. There are more than four students between Rina and Tina.
How many people are standing between Anita and Tina?

A, B, C, D, E , F, G and H are sitting around a circle facing the centre. B is the third to the right of A, who is third to the right of C. F is second to the right of E, Who is not the nearest neighbour of B. D is second to the left of H, Who is second to the left of G.

Who is sitting at the second to the left of A?

A, B, C, D, E, F, G and H are sitting around a circular table facing the centre but not necessarily in the same order. 

C is an immediate neighbour of both G and A. E sits second to left of C. Two people sit between E and H. B is an immediate neighbour of G. Only one person sits between B and F.

Four of the following five are alike in a certain way and thus form a group. Which is the one that does not belong to that group?

A, B, C, D, E , F, G and H are sitting around a circle facing the centre. B is the third to the right of A, who is third to the right of C. F is second to the right of E, Who is not the nearest neighbour of B. D is second to the left of H, Who is second to the left of G.Who is sitting at the immediate left of B?

To prepare a sweet, you need 5 cups of milk and 3 cups of sugar. If you are given 25 cups of milk, how much sugar will you need to prepare the sweet and exhaust all the milk? 

Select the group that has the same relation between the given numbers as the relation between the following group numbers.
(4, 9, 37)