$B$ is twice as old as $A$ but twice younger than $F$. $C$ is half the age of $A$ but twice the age of $D$. Which two persons form the pair of oldest and youngest?

In an examination question paper,there are $5$ items each under list $A$ and list $B.$ The examinees are requested to match each item under list $A$ with its corresponding item under list $B.$ Further it was given that
$(i)$ No examinee has given the correct answer.
$(ii)$ Answers of no two examinees were identical. Find the number of examinees attended the test paper.

The sum of the incomes of $A$ and $B$ is more than that of $C$ and $D$ taken together. The sum of incomes of $A$ and $C$ is the same as that of $B$ and $D$ taken together. Moreover,$A$ earns half as much as the sum of the incomes of $B$ and $D$. Whose income is the highest?

Rohit,Kunal,Ashish,and John are students of a school. Three of them stay far from the school and one near it. Two study in class $IV$,one in class $V$,and one in class $VI$. They study Hindi,Mathematics,Social Science,and Science. One is good at all the four subjects while another is weak in all of these. Rohit stays far from the school and is good at Mathematics only,while Kunal is weak in Mathematics only and stays close to the school. Neither of these two nor Ashish studies in class $VI$. One who is good at all the subjects studies in class $V$. Which two boys are good at Mathematics?

There are six persons $A, B, C, D, E$ and $F$ in a school. Each of the teachers teaches two subjects,one compulsory subject and the other optional subject. $D$'s optional subject was History while three others have it as a compulsory subject. $E$ and $F$ have Physics as one of their subjects. $F$'s compulsory subject is Mathematics,which is an optional subject for both $C$ and $E$. History and English are $A$'s subjects,but in terms of compulsory and optional subjects,they are the reverse of $D$'s. Chemistry is an optional subject of only one of them. The only female teacher in the school has English as her compulsory subject. What is $C$'s compulsory subject?

$(A)$ $P, Q, R, S$ and $T$ are sitting in a circle facing the centre.
$(B)$ $R$ is immediate left of $T.$
$(C)$ $P$ is between $S$ and $T.$
Who is to the immediate left of $R$?