So, I know this is a simple example and I can see everyone pretty much got it right, and probably those that didn't actually made some sort of clicker error is my guess.

分别是质子和电子,我知道这是个很简单的问题，你们大部分人都做对了,我猜那些没做对的大概是因为点错了。

麻省理工公开课 - 化学原理课程节选