If you say my name, I will no longer exist. What am I?

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

What jumps when it walks and sits when it stands?

Which three-digit number, made of consecutive digits, like 567, is 2 less than a cube and 2 more than a square?

Find the missing number in the image below.

A man has a barrel filled with oil that weighs 100 pounds, and then he puts something into it. Now the barrel weighs less than 100 pounds. What did he put in the barrel?

A man wants to cross the pit of fire which is 25 feet in length and he has 2 planks(fire resistant) 19 feet in length. How can he cross the pit of fire alive?

There was an aeroplane crash, every single person died, but two people survived. How is this possible?

What are the 50th, 63rd and 100th numbers in the sequence below?
4, 5, 8, 8, 9, 9, 12, 13, 13, 13, 17, 18, ...

There are six people in a family namely M, N, O, P, Q and R.

R and O are brother and sister.

N is the brother of Q's husband.
P is the father of M and grandfather of R.

How many male members are in the family?