Which factor varies between the isotopes of an element?

A. proton number

B. electron number

C. neutron number

D. electrical charge

Two cyclists leave towns 120 km apart at the same time and travel toward each other. One cyclist travels 10 km/h slower than the other. If they meet in 2 hours, what is the rate of each cyclist?

As a science project, you drop a watermelon off the top of the Empire State Building. 320 m above the sidewalk. It so happens that Superman flies by at the instant you release the watermelon.

Where do scientists believe the missing carbon is going? Why are they not sure?

What happens to a light ray if it is incident on a reflective surface along the normal? A. The incident ray retraces its original path. B. The incident ray is reflected perpendicular to the normal. C.

Which part of the earth is considered to be the center

A light ray is incident on a reflecting surface. If the light ray makes a "35°" angle with respect to the normal to the surface, what is the exact angle (in degrees) made by the reflected ray relative to the normal?

Reimbursement means that a client is A. able to apply for healthcare insurance and refunded for a partial sum of the payment plan by the state. B.

Meg runs a 10km race in 45 minutes (0.75 hours). What was her speed in kilometers per hour? a. 22 km/hr b. 7.5 km/hr c. 4.5 km/hr d. 13 km/hr

If you are an astronaut slowly drifting away from the space station, you might be able to drift back to the station by throwing a 555-kg tool rapidly in the direction that you are traveling (away from the station) A. False B. True C. Don't ask me D.

The loss of an electron from a neutral helium atom results in