The photon starts out as a gamma ray. What does it change into while moving in the radiation zone

What best explains the inability for life to exist in earth early atmosphere

What is the key to the recognition of codominance?

Ihave no idea how to solve these. plus there's another question that is 2) a 10 kilogram meteorite is collected in space and brought back to earth. it is composed of 1.25 kg of uranium-238 and 8.75 kg of lead-206. how many u-238 half lives have passed? what is the approximate age of the meteorite?