Why Aeroplane windows are round?

Whats the next number in the below number sequence pattern.

My cousin lives in one story house in Antarctica. His house is made the of-of sandstone. what is the color of stairs?

Can you name three consecutive days without using the words Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, or Sunday?

Can you count the number of squares in the figure below?

Name a key which is hardest to turn.

What breaks yet never falls, and what falls yet never breaks?

There are three light switches outside a room. One of the switches is connected to a light bulb inside the room.
Each of the three switches can be either 'ON' or 'OFF'.

You are allowed to set each switch the way you want it and then enter the room(note: you can enter the room only once)

Your task is to then determine which switch controls the bulb?

Eight of us go fourth, not back, to protect our king from an attack. What are we?

Replace The Question Mark Below With the Correct Number.

2 {38} 3
4 {1524} 5
6 {3548} 7
8 {????} 9