$A, B, C, D, E$ and $F$,not necessarily in that order,are sitting on six chairs regularly placed around a round table. It is observed that:
$1$. $A$ is between $D$ and $F$.
$2$. $C$ is opposite $D$.
$3$. $D$ and $E$ are not on neighbouring chairs.
Which of the following pairs must be sitting on neighbouring chairs?

In a group of six women,there are four table tennis players,four postgraduates in economics,one postgraduate in commerce,and three bank employees. Vimala and Kamala are among the bank employees,while Amala and Komala are unemployed. Komala and Nirmala are among the table tennis players. Amala,Kamala,Komala,and Nirmala are postgraduates in economics,of whom two are bank employees. If Shyamala is a postgraduate in commerce,who among the following is both a table tennis player and a bank employee?

$(i)$ There are seven books,one each on Psychology,Hindi,English,Sociology,Economics,Education,and Accountancy,lying on a table one above the other.
$(ii)$ Sociology is on the top of all the books.
$(iii)$ Accountancy is immediately below Education,which is immediately below Sociology.
$(iv)$ Economics is immediately above Psychology,but not in the middle.
$(v)$ Hindi is immediately below Psychology.
Which three books are between Accountancy and Hindi?

Four young men $Raj$,$Prem$,$Ved$,and $Ashok$ are friendly with four girls $Sushma$,$Kusum$,$Vimla$,and $Poonam$. $Sushma$ and $Vimla$ are friends. $Ved$'s girlfriend does not like $Sushma$ and $Vimla$. $Kusum$ does not care for $Ved$. $Prem$'s girlfriend is friendly with $Sushma$. $Sushma$ does not like $Raj$. With whom is $Sushma$ friendly?

After interchanging seats with $E$,who will be the neighbours of $D$ in the new position?

$A$ truck,a car,and a motorcycle have equal kinetic energies. If equal stopping forces are applied and they stop after traveling a distance of $X$,$Y$,and $Z$ respectively,then: