4. If you start with 100 atoms of Carbon-14 and 10,000 years pass - how much Carbon-14 will be left? (Show your work) (I'm not sure what sure what subject to put this under as it's my earth and space science class)​

Look at the spectrums of a star moving towards earth and a motionless star. which of these is a correct inference that can be draw from the observation of the two spectrums? (2 points) the spectrum of a motionless star is difficult to be viewed separately using oridinary telescopes. the spectrum of a motionless star is identical to the spectrum of a star which moves towards earth. the spectrum of a star shifts towards the red region when the star moves towards earth. the spectrum of a star shifts towards the blue region when the star moves towards earth.