Which of these statements is true about plant and animal cells during the process of cell division?

Several billion years ago which gas was the least prevailant in the atmosphere

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?

Fredrick griffith made a scientific discovery in 1928