Before the krebs cycle can proceed, pyruvic acid must be converted into (a)citric acid (b)glucose (c)acetyl coa (d) nadh

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?