In the series,$6, 4, 1, 2, 2, 8, 7, 4, 2, 1, 6, 3, 8, 6, 2, 1, 7, 1, 4, 1, 3, 2, 8, 6$,how many pairs of alternate numbers have a difference of $2$?

Ram remembers that Lakshman's birthday is after $19^{th}$ but before $22^{nd}$ November,whereas Anil remembers that Lakshman's birthday is after $20^{th}$ but before $24^{th}$ November. Which day is Lakshman's birthday?

Abhishek ranks thirteenth in a class of thirty-one students. What is his rank from the last (in $19^{th}$)?

In a row of boys,Deepak is seventh from the left and Madhu is twelfth from the right. If they interchange their positions,Deepak becomes twenty-second from the left. How many boys are there in the row?

$L, M, N$ and $P$ are sitting around a circle and facing the centre. $P$ is to the immediate left of $N$. $L$ is between $N$ and $M$. What is the position of $M$?

Manisha ranked sixteenth from the top and twenty-ninth from the bottom among those who passed an examination. Six boys did not participate in the competition and five failed in it. How many boys were there in the class?