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

How many letters are in the alphabet?

I am a type of vehicle that has two wheels and is powered by humans. What am I?
Hint 1: You can ride me for exercise.
Hint 2: I am environment-friendly.

When I get multiplied by any number, the sum of the figures in the product is always me. What am I?

I have a head like a cat and feet like a cat, but I am not a cat. What am I?

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

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?

The first two letters signify a male, the first three letters signify a female, the first four letters signify a great, while the entire world signifies a great woman. What is the word?

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

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