How many particles are present in 7.8 moles of a substance

At 20°c, a sample of h2o liquid and a sample of co2 gas each have the same average kinetic energy. why is one a liquid and the other a gas at this temperature?

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?

In as 1°, 2°, 3°, or 4°. be to . : °b: °c: °d: ° : °b: °c: °d: ° : °b: °c: °d: °e: °f: °g: °h: ° : °b: °c: °d: °e: °f: °g: °h: °i: °