What does an atomic number describe?

The number of nuclei

The number of protons

The number of neutrons

The number of electrons

Which of the following causes air pollution inside the house? A Smoking cigarettes B Growing house plants C Opening shades to let sunlight in D Using fans to circulate air

In an experimental technique for treating deep tumors, unstable positively charged pions (π +, elementary particles with a mass of 2.25*10-28kg) penetrate the flesh and disintegrate at the tumor site, releasing energy to kill cancer cells.

Mechanical waves are classified according to a. their size. b. their shape. c. how they move. d. their source.

Relate the changes in molecular motion of particles as hey change from solid to liquid to gas.

A powered winch is used to pull a sailboat to shore. The winch uses a 900 W motor. If the motor is used for 30 s, how much work does it do? (Power: P = W/t) 0.03 J 30 J 960 J 27,000 J

34. A steam engine operates between 300K and 600K, the maximum possible efficiency of this engine is a. 100% b. 75% c. 50% d. 25%

How many moles of phosphorus trichloride are in 200 grams of the molecule? 62.67 mol 27,466.6 mol 1.46 mol 0.69 mol

A starship passes Earth at 80% of the speed of light and sends a drone ship forward at half the speed of light rela - tive to itself. Show that the drone travels at 93% of the speed of light relative to Earth.

Rubies are used in electronics

Two kids are on a merry-go-round that is turning at a constant rate. ariel is near the outer edge, and bob is closer to the center. ariel has answer (smaller, the same, or greater angular speed?