The scientific explanation that suggests the universe is expanding relies on two main concepts

a. the doppler effect and redshift
b. redshift and blueshift
c. redshift and gravitational pull
d. doppler effect and quasars

The drawing represents the movement of particles in a substance. what changes of state can this substance undergo

Plz choose one of the compounds from the table and explain how you know the numbers of atoms in your formula. is it possible for two different compounds to be made from the exact same two elements? why or why not? with a limited number of elements (less than 120 are known), does this mean we also have a small number of compounds or do we have a large number of compounds in this world?

Which of these would be caused by a chemical change? a) the formation of lava. b) sedimantary rock layering over time. c) metamorphic rock forming from igneous. d) metamorphic rock eroding to form sedimentary rock.