These are the first 20 elements on the periodic table which of these elements had 20 protons in its nucleus (atomic number = 12)? 1. He

2. S

3. Mg

4. C

Consider hydrogen in an excited state n = 5n=5 that emits photons to reach the ground state. there are various possible transitions other than straight to the ground state that can occur; for example, it can drop to the n = 3n=3 state followed by the n = 3n=3 to the ground state transition. which of the possible transitions will result in the emission of a photon in the visible region?