Replace the question mark with the correct number in the below-given picture?

What jumps when it walks and sits when it stands?

I have branches, but no fruit, trunk or leaves. What am I?

How high do you have to count before you use the letter “a” in the English spelling of the whole number?

Prove that twice of ten is the same as twice of eleven.

The horse jumps over the king.
Strangely there is absolutely no scratch on him.

Can anyone explain, how is this possible?

In which direction should the missing arrow point?

Who always enjoys poor health?

A man has to get a fox, a chicken, and a sack of corn across a river.

He has a rowboat, and it can only carry him and one other thing.
If the fox and the chicken are left together, the fox will eat the chicken.
If the chicken and the corn are left together, the chicken will eat the corn.

How does the man do it?

I can write cow in 13 letters.

Can You?