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

What is the four-digit number in which the first digit is one-third the second, the third is the sum of the first two, and the last is three times the second?

You are presented with three boxes. One of them has a red ball inside and the other two have a black ball inside each of them. You are asked to pick up the one with red ball and you pick one. Now, one of the other boxes is opened and it is found to have a black ball.

You are presented with a chance to change your box with the one that is left closed. Will you change your box? Why or why not?

A four-digit number (not beginning with 0) can be represented by ABCD. There is one number such that ABCD=A^B*C^D, where A^B means A raised to the B power. Can you find it?

In which direction should the missing arrow point?

I’m light as a feather, yet the strongest person can’t hold me for five minutes. What am I?

Why is Saturday stronger than Monday?

I am a type of food that is often found in the fridge and can be white in colour. What I am?
Hint 1: I am a dairy product.
Hint 2: You can spread me on the bread.

How many words can a pen with half refill write?

My friends called me Iron59 because my parents are a chemist and a mathematician. What is my real name?