Can you name some countries which do not have the alphabet 'A' in them?

Can you find a pattern and the missing number in the series given below?

100, 155, 258,? , 584, 819.

A famous swimmer can swim downstream in a lake in exactly 40 minutes with the lake current.
He can swim upstream in that lake in exactly 60 minutes against the lake current.
The length of the lake is 2 km.

How long he can cover the distance of one side at a still lake with no current?

Once while in his court, King Akbar asked Birbal to write something on a wall that makes one sad when read in good times and makes one happy when read in sad times.

He took only a few moment and wrote something that fit the requirements. What did he write?

A pond had 60 fish, out of which, all but 20 died.
How many fishes are now present in that pond?

Which point will the car reach to go out?

What has six faces, but does not wear makeup, has twenty-one eyes, but cannot see?

A tree doubled in height each year until it reached its maximum height over the course of ten years. How many years did it take for the tree to reach half its maximum height?

I am a word of 12 alphabets.

* Alphabets 12, 4, 7, 2, 5 : Eastern beast of burden
* Alphabets 1, 8, 10, 9 are street made famous by Sinclair Lewis.
* Alphabets 11, 3, 6 are past.

On whole it means a person suffering from delusions of greatness.

What Is it ?

By what process could you make a 'Tea-Table' into food?