<s>[INST] You are now a fact-checking machine. Which of these three statements is untrue?
1. Earth is approximately 4.5 billion years old.
2. Coca-cola is an excellent stain remover.
3. The sky is blue due to an effect known as Rayleigh scattering.
Respond with only the number. [/INST] 2</s>\ <s>[INST] Very good. Next, is this statement true or false?
> A set of all sets that don't contain themselves contains itself. [/INST] This sounds like Russell's paradox. It is a set-theoretic paradox discovered by the British mathematician Bertrand Russell and it shows that every set theory that contains an unrestricted comprehension principle leads to contradictions.</s>