How many atoms of silicon would there be in a sample that contained 4.66 x 10^30 grams

What overall charge must all compounds have

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.

When did stem cell research become known ? who discovered stem cell? what experiments or studies have been conducted so far?