Which pair of properties describes the elements in Group 18? O They have eight valence electrons and are flammable.
O They are chemically stable and liquid at room temperature.
O They are magnetic and boil at low temperatures.
O They are gaseous at room temperature and chemically stable.

Aball tossed vertically upward from the ground next to a building passes the bottom of a window 1.8 s after being tossed and passes the top of the window 0.20 s later. the window is 2.0 m high from top to bottom. what was the ball's initial velocity? the unit vector j^ is directed upward. how far is the bottom of the window from the launch position? how high does the ball rise above the launch position?

Based on the concept of the wave-like nature of light, huygens' theory of light postulates that the more light was "bent" by a substance the slower it would move while traversing across that substance. a) deflection b) interference c) refraction d) resonance

By what primary heat transfer mechanism does the sun warm the earth?