When air is cooled, Select one: :
A. it contracts and sinks to the surface, creating an area of high pressure

B. it contracts and spreads out

C. the particles in it become more actives, causing an unstable condition

D. it contracts and sinks, creating an area of low pressure​

Which of the following statements does not describe shi huangdi? a. shi huangdi was the first emperor of the qin dynasty. b. shihuangdi wrote the lunyu, the most important text in confucianism. c. shihuangdi conquered city-states to unite china. d. shihuangdi began the process of building the great wall of china.