What does this rebus puzzle means ?

Can you find out the remainder when 3^300 is divided by 5?

I am weightless, but you can see me. Put me in a bucket, and I'll make it lighter. What am I?

What is the largest number you can write with just 3 digits?

A man walked into a pub and went straight towards the Barman. He asked for a dirty martini from the Barman. The Barman thought something and then pulled out a pistol from his drawer and aimed it directly at the man. Why did he do that?

Three fair coins are tossed in the air and they land with heads up. Can you calculate the chances that when they are tossed again, two coins will again land with heads up?

You need to complete the maze by entering from the entrance marked below in the figure near the yellow circle, bottom left and leaving from the exit point near the green circle, bottom middle.

Rule of Game: You can move only by exchanging green and yellow circles.

Five thieves looted a bank and they ran away in a car. The bank staff informed the police and they began the search of their car in their jeep. They found them on a road and chased them eventually catching them. The light that is used to fill the number plate was broken on the thieves' car. Also, the headlights of the jeep police were not working. How were the police able to catch the thieves then?

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

This puzzle is for Harry Potter fans. Do you know why Tom Riddle is called Lord Voldemort?