Solution:

Bad Intention (BAD in TENTION).

Solution:

A B C
E F G H
I J K L
M N O P
R S T
5 horizontal rows
4 vertical columns
4 diagonals with slope 1 (ROL, NKH, MJG, IFC)
4 diagonals with slope -1 (SNI, TOJE, PKFA, LGB)
2 knight's move diagonals with slope -2 (AJS, BKT)

Solution:

G = 'Roger Federer'
H = 'Rafael Nadal'

#A spoke the truth and the rest lied.

Solution:

First come, first served

Solution:

2024

Seven occurrence
24-01-24
12-02-24
08-03-24
06-04-24
04-06-24
03-08-24
02-12-24

Solution:

Because he was born before 1947(before pakistan exists) and hence is an indian citizen

Solution:

As noted, all three are 140 years old. Thus, a+b+c=140, where a is grandfather, b is son, and c is grandson. Additionally, grandson being about as many days old as son is in weeks gives 365c=52b. Finally, the grandson being as many months as I am in years gives 12c=a. Thus, the following are known.

a+b+c=140
365c=52b or b=365c/52
12c=a

By calculation and substitution we have as follows.

12c + 365c/52 +c = 140
624c + 365c + 52c = 7280
1041c = 7280
c = 6.99, or 7 (teaser said 'about')
so, as 12c = a, then a = 84.

I am 84 years old.
As an aside, my son is 49

Solution:

the seven seas

Solution:

Newspaper delivery man was the murderer because of absence of Wednesday and Thursday missing newspaper.
This indicates he already know that there is no one to read it.

Solution:

120 times