Six friends A, B, C, D, E and F are sitting in a row facing East. 'C' is between 'A' and 'E', 'B' is just to the right of 'E' but left of 'D', 'F' is not at the right end. Which pair is sitting by the side of, 'D'?

Draw a figure on the basis of above given question ,
C is between A and E, B is just to the right of E but left of D , F is not at the right end.
As shown in figure , E is between B and C
Sitting sequence :-

According to question,
The Pigeon is to the right of the Parrot. The Sparrow is above the Parrot. The Crow is next to the Pigeon. The Crane is below the Crow.
It shows that Pigeon is at the centre .
Sitting arrangement :-

According to question,
We can draw a figure , in which E is to the left of B, but on the right of A. F is on the right of B but is on the left of G who is to the left of C.
From it is clear that , the members B and F are sitted right in the middle.
Sitting arrangement :-

Draw a figure on the basis of above given question ,
A is to the immediate left of B, but on the immediate right of D. Q is on the right of A but is on the left of S, and T is on the left of V , who is to the left of D.
As shown in figure , the member A is sitted right in the middle.
Sitting sequence :-

According to question,
We can draw a figure , in which A is on the right of B, E is on the left of B but on the right of C and A is on the left of D.
It is clear that E is second from the left .
Sitting arrangement :-

Draw a figure on the basis of above given question ,
The student E sitting at the centre is facing only C and the student A is sitting facing the back of E. If D is sitting on the right of E.
Hence , it is clear that B is sitting on the left of E .
Sitting sequence :-

Draw a figure on the basis of above given question ,
D is between A and C. B is just right of C but left of F. E is not at the right end.
From figure , It shows that F is at the right end.
Sitting arrangement :-

According to question ,
A is 7th from the left and B is 9th from the right.
After interchanging their positions ,
Now A becomes 11th from the left.
? Total number of people in the row = A's position + B's position - 1
Total number of people in the row = 11 + 9 ? 1 = 19

According to question,
We can draw a figure , It is given in the question that Sudha is not next to Tapti. This condition must be ommittted to solve the question. As shown in figure , Padma is in the middle.
Sitting arrangement :-

According to question,
We can draw a figure , in which Shekhar is to the immediate right of Dhanush. Bala is between Basha and Dhanush. David is at the extreme right end of the row.
As shown in figure , Dhanush is standing in the middle.
Sitting arrangement :-