Can someone help me please

What layer of the atmosphere is directly above the troposphere?

Calculate the energy required to ionize a hydrogen atom to an excited state where the electron is initially in the n = 5 energy level. report your answer in kilojoules

Water undergoes a large change in density at 0 ∘ c as it freezes to form ice. calculate the percent change in density that occurs when liquid water freezes to ice at 0 ∘ c given that