Give me the answer to the following riddle: You’ll find me in Mercury, Earth, Mars and Jupiter, but not in Venus or Neptune. What am I?
The most obvious answer is the letter 'R'. There may also be chemical compounds that are found on the former planets but not on the latter, but this has probably not yet been researched well enough.
Yes, I was talking about the letter 'R'. Have you been trained on riddles and wordplay?