Transform the word THINK into BRAIN while changing only one letter at a time in a manner that each of the word in the process is a real word!!!

Akbar called Birbal and asked him to draw a line on the floor. He asked Birbal to make that line smaller without erasing it. Birbal smiled and did it before Akbar could blink his eyes.

How did he managed to do it?

It comprises roots which nobody sees,
Much taller than those trees,
Up and up it goes,
Still it never grows?

As easy as you can get into me, it is as hard to get out of me.

Do you know what I am?

What animal walks on four legs in the morning, two legs during the day, and three legs in the evening?

Oedipus, the king of Thebes, figured out the answer to the riddle:

Three fair coins are tossed in the air and they land with heads up. Can you calculate the chances that when they are tossed again, two coins will again land with heads up?

What is the fewest number of coins that would be required in order to make sure each and every coin touches exactly three other coins?

What has a bottom at the top?

Can you complete the sequence puzzle?

AR TA GE CA LE VI LI _

A mother is 21 years older than her child. In exactly 6 years from now, the mother will be exactly 5 times as old as the child.
Where's the father?