This lab had a control . which trial was control ?

Factors that can increase mutation rates a. high temps b. low temps c. food additives d. uv rays

18. which statement about cancer is true?

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?