What Am I Riddles

Question: When you say my name, I am no longer there. What am I?

Question: Looking at my face, I'm no more than six.
Look at the rest of me and I'm 21.
You'll see my twin and me in Las Vegas.
Say my name and you'd be uttering a threat.

What am I?

Question: What can you smell but not see. And can be deadly, too.

Question: he is a king who's good at measuring stuff.

Question: I am made throughout the world, I am a masterpiece. And to your ears, I am but a humble feast. I am but a traveler, depicted through paper as a start, I can even be made through the work of your heart. What am I?