Help me please!!! Convert 2.68x10^12 nm^2 to km^2 Write answer with correct number of significant figures and use scientific notation in your answer!!

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.

What is the percentage of hydrogen in c2h4

Which sample at stp has the same number of atoms as 18 liters of ne at stp