Plz I need help with dis assignments​

When the earth was formed and cooled, why did nickel and iron end up in the center of the earth while basalt and granite ended up in the outer layers

Smog is the term used to describe the combination of fog and smoke

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.