Why Aeroplane windows are round?

Look at this sequence from top to bottom. What is the next number in the sequence?
1
11
21
1211
111221
312211

Two in a corner, one in a room, zero in a house, but one in a shelter. What am I?

There are three Athletes (John, Tarun and Harish) and their individual Coaches (Jacob, Meenaxi and Priyanka) standing on the shore.
No Coach trusts their Athlete to be near any other Coach unless they are also with them.
There is a boat that can hold a maximum of two persons.
How can the six people get across the river?

Can you find the next number in the below sequence
3 , 7 , 10 , 11 , 12 , 17 ?

When I got four, I have it none.
When I got two, I have it some.
When I got none, I have it all.

What is it?

What is the coolest letter in the alphabet?

It is a 5 letter word if you take away first letter it is something you get from sun, if you remove second letter you will get something to eat, if you remove third letter you get a word you use in pointing at and if you remove the fourth letter you get something to drink. What is it?

Identify The phrase in the picture.

There are nine dots in the picture that has been attached with this question. Can you join all the dots by drawing four straight lines without picking up your pen?