What work can one never finish?

In four steps you need to move the word 'cold' From 'warm' by replacing one alphabet at a time such that every word formed at each step is acceptable in English Dictionary.

In my garden, I have many trees but only one of them is the mango tree. In these mango trees, there are some mangoes(as expected).

But after a strong wind, there are neither mangoes on the tree nor on the ground. Explain?

What is a word made up of 4 letters, yet is also made up of 3. Sometimes is written with 9 letters, and then with 4. Rarely consists of 6, and never is written with 5.

You can see three almost identical images below. Can you spot the odd one out from them?

You are a cab driver who pools passengers. You pick 3 people from a destination and drop 1 after an hour. 2 people climb aboard at the same time and you drop 3 at the next destination. After some time, you pick 2 passengers only to drop 1 after a short distance where 3 more passengers climb up the cab. You leave the rest of the passengers one by one to their destination and then come back home.

Can you tell the eye color of the cab driver?

How can you spell "White of an egg" in one word?
Hint: I know you can spell coke, poke, and joke.

In the given figure, move three matchsticks so that the resulting figure contains two rectangles.

Can you name an animal whose killing cannot be performed without spilling your own blood?

Can you find a number that lies one third of the distance between 1/3 and 2/3?