An element is a substance
A. Mixed
B. Pure
C. Combined
D. Human-made

Clouds form when water vapor to form small droplets. a. humidifies b. condenses c. evaporates d. precipitates

Determine the wavelength of the light absorbed when an electron in a hydrogen atom makes a transition from an orbital in the n=3 level to an orbital in the n=7 level.

What are the spectator ions in 2h+ + so42- + ca2+ + 2r → caso4 + 2h+ + 21?