Imagine you needed to identify if an object has undergone a physical change or a chemical change. What information would you need to know, and how would you decide?

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?

From the choices provided below, list the reagent(s) in order that will react with cyclopentanone to form the compound shown below.

How many atoms are in 2 moles of phosphorus