What is the change in atomic mass number when an atom emits an alpha particle?
a.
decreases by 2
c.
increases by 2
b.
decreases by 4
d.
increases by 4

Electric charge is what ? a. kinetic energy b. radiation c. discovery d. electricity

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.

Which class of molecules functions as chemical signals? hormones water carbohydrates proteins