What has many keys but can’t open a single lock?

John named his first son Alpha, second Beta, third Charlie and fourth Delta. What is the fifth son's name?

There are three boxes on a table. One of the box contains Gold and the other two are empty. A printed message contains in each box. One of the message is true and the other two are lies.

The first box says "The Gold is not here".

The Second box says "The Gold is not here".

The Third box says "The Gold is in the Second box".

Which box has the Gold?

If one and a half boys, eat one and a half burgers in one and a half hours.

How many burgers can 9 boys eat in 3 hours?

What has one letter and starts with an E?

Alpha is Beta's sister.

Gamma is a Beta mother.

Delta is Gamma's father.

Tango is Delta's mother.

Then,

How is Alpha related to Delta?

Why is it very easy to weigh a fish?

Always in you, Sometimes on you;

If I surround you, I can kill you.

What am I?

Can you make a fire with just a single stick?

I add 5 to 9 and get 2. The answer is correct, so what am I?