# A Mysterion Affair

Chemistry Level 4

Suppose that we have a hydrogen atom. If we take its one electron and replace it with another particle (let us call it the $$Mysterion$$) that carries the same charge but has double the mass of the original electron, which of the following are true? {assume that the existence of such a particle is purely for the sake of the question}

• (1) The speed of the $$Mysterion$$ in a shell will be equal to the speed of the electron that was in the same shell.
• (2) The radius of the 3rd orbit will be same for both the electron as well the $$Mysterion$$.
• (3) Energy gap between the levels of the hydrogen atom will not change.
• (4) The ionization energy of the atom, needed to remove the $$Mysterion$$ will not change.

What is the sum of the correct option numbers?