Prehistory can be described as
what happened last year
what happened millions of years ago
the time prior to the use of written records

Amixture of gaseous sulfur dioxide and oxygen are added to a reaction vessel and heated to 1000 k where they react to form so3(g). if the vessel contains 0.669 atm so2(g), 0.395 atm o2(g), and 0.0851 atm so3(g) after the system has reached equilibrium, what is the equilibrium constant kp for the reaction: 2 so2(g) o2(g) ⇌ 2 so3(g)

The density of a planet is 0.69 g/cm3 (density of water is 1.0 g/cm3). which of the following planets might this be? a. mercury b. venus c. saturn d. mars

What is the area in square meters of 448 g ai foil that has a thickness of 23921 nm? the density is 2.70 g/cm