What has a ring but no finger?

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.

The king of Octopuses has servants who have six, seven or eight legs. The distinguishing characteristics of the servants is that the one with seven legs always lie but the one with either six or eight legs speak the truth always.

One day, four servants meet and converse:

The black one says, 'We have 28 legs altogether.'

The green one says, 'We have 27 legs altogether.'

The yellow one says, 'We have 26 legs altogether.'

The red one says, 'We have 25 legs altogether.'


Can you identify the colour of the servant who is speaking the truth?

Can you start the fire using two pieces of wood?

What is in seasons, seconds, centuries and minutes but not in decades, years or days?

An American nightclub called 'The Coconut Grove' had a terrible fire in which over 400 people died. A simple design flaw in the building led to a high death toll. Subsequently, regulations were changed to ensure that all public buildings throughout the country eliminated this one detail, which proved deadly. What was it?

Why do you find that most of the buildings are deprived of the 13th floor?

Here is a mathematical expression that also secretly tells a movie name. What movie is that?

In case you were starting to feel confident, this one was meant for third graders in Vietnam. The answer is 66, but we don't blame you for scratching your head about how they got there.

I have one of the three numbers: 1, 2, or 3 in my mind. I speak only truth. You can ask me just one question for which I will only reply in yes or no or don't know. What question will you ask from me so that you are able to know the number?