Find the Next Number in the Sequence

2 9 3 1 8 4 3 6 5 7 ?

What jumps when it walks and sits when it stands?

Count the number of triangles in the below picture?

A word I know has six letters it contains, remove one letter and 12 remain. What is it?

John was working on a Chemical Mixture whose weight comprise 90% liquid and 10% solid. The total weight of the mixture is 20 pounds. After a while, John noticed that some of the liquid evaporated and now the liquid comprises just 50% of the weight.

What is the weight of the chemical mixture now?

What does this rebus means ?

Why Aeroplane windows are round?

Can you name four days which start with the letter 'T'?

A boy and his father are caught in a traffic accident, and the father dies. Immediately the boy is rushed to a hospital, suffering from injuries. But the attending surgeon at the hospital, upon seeing the boy, says 'I cannot operate. This boy is my son.' How is this situation explained?

10+10 and 11+11 can give you the same answer.

Explain how?