With the help clues provided in the image, can you find the 5 digit key?

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

Spelt forwards I’m what you do every day, spelled backwards I’m something you hate. What am I?

How high do you have to count before you use the letter “a” in the English spelling of the whole number?

15 caves are arranged in a circle at the temple of doom. One of these caves has the treasure of gems and wealth. Each day the treasure keepers can move the treasure to an adjacent cave or can keep it in the same cave. Every day two treasure seekers visit the place and have enough time to enter any two caves of their choice.

How do the treasure seekers ensure that they find the treasure in the minimum number of possible days?

There are 2 people near the river and both of them want to get on the other side. The boat can only take one of them. But they got across.
How?

John buys rice at Rs.60/kg from Britain and then sells them at Rs.5/kg in India. As a result of this, he becomes a millionaire. How come?

What's the next in the series?

H, Be, F, S, Mn, Kr, In, Gd, Tl, ?

What is full of holes but still holds water?

It was a dark stormy night and a couple were in a car driving madly to a city. The car broke down and the husband had to go get help from someone who spoke his language. He was afraid to leave his wife alone in the car so he locked the car before leaving. When he came back, the car was in the same state as he had left it but his wife was dead, there was blood on the floor and there was a stranger in the car. What happened?