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

Consider the following:
$1.$ Saxena,David,Jain,and Kumar were District Collectors at places $P, Q, R,$ and $S$ respectively in $1970$.
$2.$ In $1972$,they were transferred; Saxena and Jain interchanged places. Kumar and David also interchanged places.
$3.$ One year later in $1973$,they were again transferred such that David and Jain interchanged places,and Saxena and Kumar were also interchanged.
What should be the next round of transfers so that all the four persons could have been posted at all the four places?

$(i)$ Jayant,Kamal,Namita,Asha and Tanmay are five members of a family.
$(ii)$ They have their birth dates from January to May,each member in one of these months.
$(iii)$ Each one likes one particular item for his/her birthday out of Bengali Sweets,Chocolates,Pastries,Ice Cream and Dry Fruits.
$(iv)$ The one who likes Pastries is born in the month which is exactly middle in the months given.
$(v)$ Asha does not like Ice cream but brings Chocolates for Jayant in February.
$(vi)$ Tanmay who is fond of Bengali sweets is born in the next month immediately after Namita.
$(vii)$ Namita does not like Dry fruits or Ice cream.
Which combination of month and item is true for Jayant?

Sitting in a row in front of a camera,$Mr. X$ is on the left of the person sitting in the centre but is on the right of $Mr. Y$. $Mr. P$ is on the right of $Mr. Z$ and $Mr. R$ is on the right of $Mr. P$. $Mr. R$ is the second person from the person sitting in the centre. Who is the person sitting in the centre?

In an examination,Raj got more marks than Mukesh but not as many as Priya. Priya got more marks than Gaurav and Kavita. Gaurav got less marks than Mukesh but his marks are not the lowest in the group. Who is second in the descending order of marks?

$A$ training college has to conduct a refresher course for teachers of seven different subjects: Mechanics,Psychology,Philosophy,Sociology,Economics,Science,and Engineering from $22^{nd}$ July to $29^{th}$ July.
$1.$ The course should start with Psychology.
$2.$ $23^{rd}$ July,being Sunday,should be a holiday.
$3.$ Science subject should be on the previous day of the Engineering subject.
$4.$ The course should end with Mechanics.
$5.$ Philosophy should be immediately after the holiday.
$6.$ There should be a gap of one day between Economics and Engineering.
The refresher course will start with which one of the following subjects?