When a physical change in a sample occurs, which of the following does not change?
a. shape
b. temperature
c. volume
d. composition

Which statement is a reason to support population regulation? a) it is unethical for us to control birth control rates b) humans have the freedom to produce as many children as desired c) the gap between the rich and poor has been narrowing since 1960 d) billions more people on the earth will intensify many environmental and social problems

In the particles are arranged in a regular, repeating pattern. a)a crystalline liquid b)a crystalline solid c)all gases d)all solids

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation: