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!!!

Two prisoners Jack and Jill are locked in a cell.
There is open window approx 40 feet above the ground of the cell.
They are never able to reach there.

Then they plan to escape by a tunnel and they start digging out.
After digging for more than 20 days, Jill comes with the different plan and they escaped.

what was the plan ?

Different lights make me strange by changing me into different sizes. What am I?

Intelligence Agency need to break the vault but the problem is that they are not able to break the vault.

On the vault, a text is written as:

31 11 33 33 43 45
21 25
31 24 11 31 51 41

To Break the code Intelligence Agency brings a mathematician named Joseph.
Minutes later he deciphers the code.

Whats the code?

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

Can anyone explain, how is this possible?

If you toss a coin 10 times and it lands heads up every time, what are the chances it will land heads up if you toss it again?

Shyla was sleeping in her apartment when suddenly a robber broke into her house. He asked her to stay quiet and started looting the cash and jewelry. Suddenly the landline phone started ringing. The robber pointed a gun at Shyla and asked her to pick up and talk without giving away the situation.

She picked up the phone and it happened to be her husband. She spoke, Is it an emergency darling? Do give me a call when your flight lands, I will prepare your favorite food that will help you relieve the stress. Then she hanged up.

10 minutes after, the police arrive at the scene and catch the robber. How did the police know about the robbery?

A donkey is behind another donkey
I'm behind that second donkey
But there is a whole nation behind me

It is a murder you can describe in a word.

Sherlock Holmes was challenged to make a pre-drawn line smaller without erasing it. He did it in fractions of seconds. How?

There is so small cabin inside a deep forest.
All the forest burned out to worst possible but the inside of the cabin is still the same.
However all the person inside the cabin die.

How come ?