Why do you find that most of the buildings are deprived of the 13th floor?

What does below chemistry rebus means?

Find the next number in the series.
1 10 24 43 67 ?

Find the next number in the series?
2, 12, 36, 80, 150, 252, 392, _ ?

You bought me for dinner but never eat me. What am I?

Replace each alphabet with the number (1-9) to make the below equation correct.

AB * C = DE - F = GH / I

In this image, you can see three almost identical Doraemon images. Can you spot the odd one out from them?

In the attached figure, you can see a chessboard and two rooks placed on the chess board. What you have to find is the number of squares that do not contain the rooks. How many are there?

How many triangles are there in the picture below?

Name a key which is hardest to turn.