Which is an example of matter in a plasma phase?
A) dry ice
B) a torch flame
C) molten lava
D) liquid hydrogen
E) none of the above
Question 2
An umbrella tends to move upwards on a windy day principally because
A) trapped air under the umbrella, warms, and rises.
B) buoyancy increases with increasing wind speed.
C) air pressure is reduced over the curved top surface.
D) all of the above