Solution:

As we can catch 'Cold', 'Hot' is definitely faster.

Solution:

There are only four cats. The room is too small and each cat is sitting at the tail of other.

Solution:

The wife booked a two way ticket for herself and booked a one way ticket for her husband.

Solution:

Trojan evidently was the one buried.

Solution:

It is simple. The sheriff never told him where the crime scene was. But still he reached at the right place. This points towards the fact that he knew it already and that he is the killer himself.

Solution:

3^2 = 4 + 5
(^ is used for squaring the term, it is not used here as a mathematical symbol.)

Solution:

Seven chairs are required as there are only seven people in the room.
A Grandfather married to Grandmother.
They are blessed with a son who is married to a woman.
Together, they have three children a handsome lad and two beautiful angels.

Thus, only seven people are present.

Solution:

Scent, Cent and Sent.

Solution:

NEELAM.

Explanation:
Just read the car's number upside down and you will know why.

Solution:

17

Explanation:
Let us say that the smallest of the square is of 1 unit side.
We have 6 such squares. Now moving up, if we see the squares with side 2 units, we have 8 of them. Similarly we have 2 squares with side 3 units and 1 square with side 4 units.

6 + 8 + 2 + 1 = 17 squares.