Name a key which is hardest to turn.

A man dies of old age on his 25 birthday. How is this possible?

A girl was sitting in her hotel room when she heard a knock on the door. She opened the door and found that a man was standing outside.
The man said, "Oh! I am really sorry, I thought this was my room."
He then walked through the corridor to the elevator. The girl did not know the man. She closed her door and called security asking them to apprehend the man.
What made her suspicious of that man? He might have been genuinely mistaken.

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

What has six faces, but does not wear makeup, has twenty-one eyes, but cannot see?

What has one eye, but can’t see?

Three people are in a room. Ronni looks at the Nile. The Nile looks at Senthil. Ronni is married but Senthil is not married. At any point, is a married person looking at an unmarried person? Yes, No or Cannot be determined.

Christina has four daughters, and each of her daughters has a brother. How many children does Christina have?

In 1990, a person is 15 years old. In 1995, that same person is 10 years old. How can this be?

A professor thinks of two consecutive numbers between 1 and 10.
'A' knows the 1st number and 'B' knows the second number

A: I do not know your number.
B: Nor do I know your number.
A: Now I know.

What are the four solutions for this?