Which of the following could be true of two species that have a competitve ralationship in the same ecosystems me out a. the species preys on the other b. the relationship is mutually beneficial c. they shar the same niche d. one species benefits while the other nether nor harmed

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?