What is the mass of the light bulb?

Which gas found in the earth's atmosphere greatly impacts the daily range of temperature on earth. a) oxygen b) hydrogen c) nitrogen d) water vapor

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?

When are the centromeres broken in meiosis?