According to question,
O is third from M who is standing left of N, and P is on the left of Q who is fourth from N.
As shown in figure , the position of P from right is Second .
Sitting arrangement :-

According to question,we have
Raju was shifted three places towards right
Raju's position = 3 + 8th from the right end = 11th
Total number of children = 15
? Earlier position from left = Total number of children - Raju's position + 1
Earlier position from left = 15 ? 11 + 1 = 5th

According to question,we have
Dipika's position = 11th from West
Sudesh's position = 15th from East end.
After interchanging their positions ,
Sudesh's current position = 9th from East end.
? Total number of persons in the row = Dipika's position + Sudesh's current position - 1
Total number of persons in the row = 11 + 9 ? 1
Hence ,total number of persons in the row = 20 ? 1 = 19

According to question,
We can draw a figure , in which Ankit is sitting to the immediate right of Anjum. Amit is sitting to the left of Priya and to the immediate right of Ram. Ram is sitting to the right of Ankit.
From given figure it is clear that , Priya is sitting at the extreme right end .
Sitting arrangement :-

According to question,
We can draw a figure, in which A is to the left of B but on the right of C. D is to the right of B but on the left of E.
Therefore ,D and E are at the extremes .
Sitting sequence :-

Draw a figure on the basis of above given question ,
C is standing between A and G. B is standing to the left of E. G is standing between C and E. D and F are to the right of C.
As shown in figure , C is standing in the middle.
Sitting arrangement :-

According to question,
We can draw a figure , in which C is standing between A and G. B is standing to the left of E. G is standing between C and E. D and F are to the right of C.
As shown in figure , B is standing at the extreme left.
Sitting arrangement :-

Draw a figure on the basis of above given question ,
C is sitting immediately to the left of E. A is sitting between D and E.
As shown in figure , B is to the immediate left hand side of C.
Sitting sequence :-

Draw a figure on the basis of above given question ,
C is sitting immediately to the left of E. A is sitting between D and E.
As shown in figure , D is sitting between B and A.
Sitting sequence :-

According to the question,
arranging the seven members in row,
H E F D C B A
Hence, D is sitting in the middle.