A sample of helium gas occupies 14.7 L at 23°C and 0.956 atm. What volume will it occupy at 40°C and 1.20 atm?

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?