Why was 1990 an important year regarding air quality?

What is the mass of 4 molecules of co2

Which statement correctly describes metallic bonds? a. they form when certain atoms lose electrons and other atoms gain electrons. b. they involve an attraction between anions and cations. they always involvpoth a metal and a nonmetal. d. they can only form between atoms of the same element. e. they form because electrons can move freely between atoms.

When the mercury level in a barometer decreases that atmospheric pressure has