How many grams of iron are produced when 450 grams of Iron (III) oxide reacted?​

Name the element in group 17, period 2. (periodic table)

How many moles of potassium hydroxide are needed to completely react with 2.94 moles of aluminum sulfate

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?