Please help ASAP. If you know the answer to few of the parts then tell me the answer to the part you know with explanation and also type the letter of which part you solved

In a floral arrangement, the focal area is often

Achange in the number of neutrons in an atom will change an blank . when the number of protons changes in an atom, a new element will form.

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?