If you had a pizza with crust thickness 'a' and radius 'z', what's the volume of the pizza?

A Japanese ship is sailing in the Indian Ocean. The captain of the ship feels tired and decides to take shower to be rejuvenated. He goes to take the shower after keeping his diamond-studded Rolex watch and gold chain on the table.
When he comes back after 15 minutes, he finds them missing. There are 4 crew members on the ship and he calls them one by one to ask them what they were doing in that duration.

Following are the answers:
1. Crew 'A' who is the cook replies that he was cooking mutton for the crew members.
2. Crew 'B' who is a housekeeper tells that he was sleeping in his room.
3. Crew 'C' who is the engineer says that he was checking on the generator.
4. Crew 'D' who is another housekeeper says that he was correcting the hoisted flag that was put upside down.

It took only a couple of seconds for the captain to find the thief. Can you find the thief too?

You walk into a room that contains a match, a kerosene lamp, a candle and a fireplace. What would you light first?

Can you solve the maths in the below-given picture equation?

Find the Next Number in the Sequence

2 9 3 1 8 4 3 6 5 7 ?

When does a USA Potato change its nationality?

Yesterday I fell from 30 feet high ladder but I don't get hurt. Why?

I speak without a mouth, and hear without ears. I have no-body, but I come alive with the wind. What am I?

Below toothpicks/matchsticks indicate the group of fishes moving from west to east direction. Can you make them move from east to west by just moving three toothpicks/matchsticks?

How can you make a TV, a bed, a dog, and a car liquid?