What is the word or phrase?

What you cannot hold but it is yours?

What does this rebus riddle means ?

On a special event at the prison, 5 prisoners John, Jacob, Krist, Tang, and Dang given a chance to go to a sauna and can bring one thing with them.

Following are the things that the prisoners bring with them.
John: A soda
Jacob: Thermos
Krist: Book named "How to kill"
Tang: A Walkman
Dang: Harmonica

Since it is a Sauna, no one can see each other. After a while When the steam is switched, Tang was found dead and there was blood all around.
J Bond was called and he instantly come to know who can be the murderer. How?

Can you find the thief by just looking at the picture below?

What have one eye but still cannot see?

My first is in chocolate but not in ham. My second is in cake and also in jam. My third at tea time is easily found. Altogether, this is a friend who is often around. What is it?

You see a mathematical expression in the picture. Can you think of a movie that this expression refers to?

How many triangles are there in the picture below?

What has many teeth, but cannot bite?