There are only two naturally occurring isotopes of helium on earth. If you increase the % abundance of helium-3, does the % abundance of helium-4 change? Why or why not?

When determining the shape of a molecule, it is important to draw a lewis dot structure first in order to see the total number a. electrons within the moleculeb. bonding and unshared pairs around central atomc. unshared pair within the molecule( i really need it )

How do i complete this electrolysis of water lab? i’m at home, so i don’t have the materials, and the lab didn’t properly work and was incomplete at school.

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.