You can take four of the five letters out of this word, but the pronunciation never changes. What is the word?

Can you find the key in the picture below?

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:

What month of the year has 28 days?

This is the oldest riddle that I have heard.

Once there was a man who was travelling with a Tiger, goat and grass.
He needs to cross a river that can carry a maximum of two i.e. Man + one of Tiger goat or grass. But the problem is "If he takes the lion with him, the goat will eat grass and if he takes grass with him, the lion will eat the goat".

How can he ensure the safe delivery of all three?

If you remove one from eleven, it becomes ten. If you remove one from nine, it becomes ten.

How is this possible?

If 5 cats catch 5 mice in 5 minutes, how long will it take one cat to catch a mouse?

A man died and leaves Rs.10,000 in his will. There are 6 beneficiaries- his 3 sons and their wives. The 3 wives receive Rs.3960 of which Priyanka gets Rs.100 more than Tanu and Neha gets Rs.100 more than Priyanka.
Pramod gets twice as much as his wife, Tushar gets the same as his wife, and Prashant gets 50% more than his wife.

Who is married to whom?

If an electric train is travelling south, then which way is the smoke going?

Make a sentence consisting of three words that have the whole alphabet.