What do you get if you add 2 to 100 four times?

I have a five and a three-gallon jar. Assuming there is an infinite supply of water, how can I measure one-gallon water?

The doctor advised his patient to take a tablet after every fifteen minutes. He gave him five tablets in total.

How much time will he take to have all the five tablets?

Can you identify the direction in which this bus is moving; left or right?

Hint: The bus is moving on the roads of London.

In the below-given picture of a pretty girl, there is something wrong. Can you find out what it is?

A man is found hanging dead from the ceiling of a room. The room’s dimensions are 15 x 15 x 15. The man is only 6ft tall and the rope was only 2ft long. There are no windows and only one door to the room. The door is bolted shut from the inside, and a puddle of water is under the man. How did he kill himself?

81 x 9 = 801. What must you do to make the this equation true?

A few friends are enjoying their sea voyage in a boat full of apples. On the way, they felt hungry and thus decided to eat the apples. Together, they ate two dozen of apples. When they have eaten the apples, will there be any change in the water level?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

I am a type of vehicle that has two wheels and is powered by humans. What am I?
Hint 1: You can ride me for exercise.
Hint 2: I am environment-friendly.