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

Which alphabet letter is a question?

You are presented with three boxes. One of them has a red ball inside and the other two have a black ball inside each of them. You are asked to pick up the one with red ball and you pick one. Now, one of the other boxes is opened and it is found to have a black ball.

You are presented with a chance to change your box with the one that is left closed. Will you change your box? Why or why not?

If I remove one from eleven it becomes Ten and if I remove one from nine also becomes Ten. How?

What is in seasons, seconds, centuries and minutes but not in decades, years or days?

I look at you, you look at me, I raise my right, you raise your left. What am I?

Two boys wish to cross a river. The only way to get to the other side is by boat, but that boat can only take one boy at a time. The boat cannot return on its own, there are no ropes or similar tricks, yet both boys manage to cross using the boat.

How?

If,

Akriti = 631
Levis = 521
Sroti = 521
Aneel = 533
Then,
Sunil =?

Decode below three cipher riddles:

26 L of the A
7 D of the W
1000 Y in a M

Complete the following series. It.s very logical:

1, 4, 5, 6, 7, 9, 11, __?