HELP!! : 2 H2 + O2 --> 2 H2O. Why isn't there any coefficient in front of oxygen? A. A one is assumed when no coefficient is present.

B. There is an unlimited amount of oxygen

C. The 2 after the oxygen is all that is needed

D. All of these

What is i fracture in the crust called when land move up, down or sideways

In apex! a liquid heated beyond a certain temperature becomes

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?