What is the riddle which can be asked all day with a different correct answer each time.

In a mathematical quiz, you are asked the following question:

Use three 9s in a mathematical expression without dividing or multiplying to form the number one.

Can you answer the question?

I am a word that begins with the letter “i.” If you add the letter “a” to me, I become a new word with a different meaning, but that sounds exactly the same. What word am I?

I came first on earth but second on the heaven.
I also came twice in a week but found just once in a year.
I stay away from months but you can find me in February.

What am I?

Who is that with a neck and no head, two arms and no hands? What is it?

You are confined in a room and given two metal rods. Out of these two rods, one is magnet and the other is the iron rod. They look starkly similar. You don't have any other metal object in the room.

How will you decide which one of those is magnet?

John speaks the truth only once a day in a week. Below are a few hints for you:

First: Days are Sunday, Monday and so on.
Second: One day he says, "I lie on Monday and Tuesday".
Third: On the next day, he says, "Today is either Thursday, Saturday or Sunday".
Fourth: On the next day, he says, "I lie on Wednesday and Friday".

Can you identify the day on which he speaks the truth?

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

There are three boxes which are labeled as Rs100, Rs150, and Rs200. One box contains two notes of Rs. 50. The second box contains one note of Rs50 and one note of Rs100 The third box contains two Rs. 100 notes. All boxes are labeled incorrectly.

What is the minimum number of boxes you must check in order to label all boxes correctly?

What is the longest word in the dictionary?