What conditions, common to most stars including our sun, appear to be necessary in order for fusion reactions to take place?

3. How many valence electrons are in the outermost energy level of each of the following elements? a. Helium b. Lithium c. Nitrogen d. Magnesium

The space shuttle is descending through the earth's atmosphere. How is the mass of the shuttle affected? A. It will remain constant. B. It will increase with descent. C. It will decrease with descent.

1.) Assuming the clay blob and the superball have the same mass, and that you throw them with the same velocity, which would you throw to close the door?

What do scientists use to divide the geologic time scale? Major divisions in the fossil records Major divisions in the sedimentary rock layers Evidence for catastrophic events in Earth's history Major changes in mineral deposits in the rock layers

What conditions are required for nuclear fusion?

Friction between solids can be most accurately defined as the force that opposes the sliding motion of two surfaces that are touching each other. A. True B. False

1. For a reaction to occur, energy must be to break chemical bonds. O A released OB converted OC absorbed

51 Mm is how many km?

What type of change occurs when water changes from solid to a liquid

Definition of artficial and natural radioactivity