Draw an octane molecule for me. Here’s pen and paper.
Surprise! You've been asked a basic chemistry question. The question is simple. You probably learned the answer in high school, if not at college. But it might be such a surprise that you can't think of the answer for a moment. That's ok. Showing a calm and thoughtful approach to a question is appropriate and appreciated by an interviewer. Think, then write it out if you know it. If you don't, go look it up, since it is the major component in gasoline.
"It's been awhile since my last chemistry class. Let's see. I know that it has eight carbon atoms (from the prefix oct- in octane) and I know that every carbon atom has four bonding attachment points. From the '-ane' part of the name, I know that there are no double bonds. I also know that it is a hydrocarbon, so every atom in an octane molecule is either a carbon or a hydrogen atom. So I will draw a chain of 8 carbon atoms, each one with a single bond to the other. That leaves three bonds to fill on the two carbon atoms at the ends of the chain, and two open positions for each of the other carbons. So I will just fill in all the hydrogen atoms - 18 of them, and that's an octane molecule."
