Radioactivity was first discovered in salts of which of the following elements?
A) sodium
B) radium
C) radon
D) uranium
B
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Carefully examine the relative positions of the lettered arrows in the diagram. Which letter corresponds most closely to the extinction of the dinosaurs?
How might you distinguish a sodium-vapor street lamp from a mercury-vapor street lamp?
A) use binoculars to look for printing adjacent to the bulb B) look at the street lamps through a spectroscope and match their spectral patterns to their respective atomic spectra C) ask your local utility company to identify these lamps for you D) The shadows cast from a sodium-vapor street lamp tend to be more diffuse around the edges.
Ecosystems are connected by ________
A) the essential flow of water through the ecosystem B) individual species competing for space with other species in the ecosystem C) the movement of pollutants between ecosystems D) the flow of energy and matter through the ecosystem E) energy cycling and nutrient flow
What happens to energy as ice changes state to a liquid?
A. There is no change. B. It is released. C. It is absorbed.