When burning petrol in motor vehicles two gases form which contribute to acid rain. what are the two gases?

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?

Which polymers are most closely related? a. protein and nucleic acids b. cellulose and starch c. nucleic acids and starch d. nucleic acids and cellulose

Which of these is a density dependent factor? a. epidemic b. earthquake c. drought d. hurricane