I have teeth but i don't bite. Who Am I ?

Two boys were admitted to a school. When the headmaster asks them about their parents, they tell him that they have same parents (father and mother). On further inquiry, it turns out that they both share the same date for their birthday.

"Are you twins," ask the headmaster.
"No," replies the boys.

Is it possible?

How can you leave a room with two legs and return with six legs?

What kind of tree can you carry in your hand?

What is the Surname of Barbie Doll?

What English word has three consecutive double letters?

Find the next number in the sequence

5 12 24 36 ?

How do you go from 98 to 720 using just one letter?

In the Chess Board picture below white army is arranged. You need to add a black army on the board such that no piece is under any threat.
Note: Army comprised of 1 king, 1 queen, 2 rooks, 2 bishops, 2 knights, and 8 pawns.

The doctor prescribed you to take one pill from the bottle every half an hour. The bottle is now left with only three pills.

How long do you think you have before you run out of pills?