Stored energy that results from position or shape of an object is

What element is able to combine with itself and hydrogen to form large molecules ?

Which of the following is the earliest era of earth's geologic time scale? cenozoic mesozoic precambrian paleozoic

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?