Which object is visible only by reflection? a) the sun b) earth's moon c) a candle flame d) a bolt of lightening

How many times did thomas edison mess up the light bulb

Carbon 14 is a naturally occurring stable

How to tell if two objects are in thermal equilibrium 1.the objects have the same temperature 2.the objects are the same size 3.the objects are touching each other 4.the objects temperatures are changing