Electrons in excited hydrogen atoms are in the

n = 3 energy level. How many different photon

frequencies could be emitted as the atoms return

to the ground state?

(1) 1 (3) 3

(2) 2 (4) 4

What must be true about tow objects if heat is flowing between them?

Which of the following represents a system that is completely open? A. a capped soda bottle B. a pot of boiling water C. a presser cooker D. a pressurized canister of helium gas

A box slides downwards at a constant velocity on an inclined surface that has a coefficient of friction uK =.58 The angle of the incline, in degrees, is most nearly:

Pure substances can be classified as blank or compounds

1. A tennis ball is dropped from a second story window. It is in free fall, accelerating downward at a rate of 9.8 m/s2. At the exact same time, another person throws a tennis ball out the adjacent window with a horizontal velocity of 30 m/s.

Which planet is 92,897,000 miles from the sun?

Stretching or drawing a solid into a wire is which of the following physical properties A) ductility B) solubility C) malleability D) conductivity

How well does the infographic ""Plastics in the Ocean"" present a solution to the problem it describes?

How does erosion move and deposit rocks

Match the word with its definition. Column A1. rotational speed 2. tangential speed 3. centripetal force 4. centripetal acceleration 5. Newton's Second Law 6. Newton's First Law Column Ba. 1 revolutions per minute (RPM) b.