What happens during the krebs cycle

Witch type of microscope is used to view very small cell components like proteins and dna?

Study this image which statement best describes the rock shown check all that apply

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?