Of the reactions involved in the photodecomposition of ozone (shown below), which are photochemical? 1. o2 (g) + hν → o (g) + o (g) 2. o (g) + o2 (g) + m (g) → o3 (g) + m* (g) 3. o3 (g) + hν → o2 (g) + o (g) 4. o (g) + o (g) + m (g) → o2 (g) + m* (g)

Americium-241 undergoes fission to produce three neutrons per fission event. if a neutron-absorbing material is mixed in with this sample so that the rate of neutron production drops down to 1.8 neutrons per fission event, which will be effective at achieving a critical mass? check all that apply. remove a deflective shield surrounding the sample. remove absorbent material mixed in with the sample. compress the sample of americium-241.