Buy me, smell me or deliver me, I do not change.

Who am I?

A woman named Maria was at the funeral of her mother. She met a nice young man that she had never seen before and after the service, they spent a bit of time together. Then she got busy and didn’t get his name or phone number before he left. She tried to find him, but no one knew who he was or how to contact him. A few weeks later, Maria’s older sister dies and the police suspect murder. Who killed the sister?

What runs around the whole yard without moving?

In four steps you need to move the word 'cold' From 'warm' by replacing one alphabet at a time such that every word formed at each step is acceptable in English Dictionary.

I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?

When it is alive we sing, when it is dead we clap our hands. What is it?

Considering the below equation:

V + II - VI = 10
IV - X + VIII = 20
IV - VII + VI = 30

Then, I + II + III = ?

There is a place where if I stand up straight, I will still be considered sideways.

There are a number of books on a shelf. If one book is the 4th from the left and 6th from the right, how many books are on the shelf?

The more you take me, the more you leave me behind.
Who Am I?