When Li-7 is bombarded with a proton, two alpha particles are released along with energy. It turns out that the mass of the two alpha particles actually weighs less than the original products in the reaction. The mass that was converted to energy is called the ________ ?

Mass Defect

When a catalyst is added to a system at equilibrium, a decrease occurs in the ______?

Activation Energy! A catalyst speeds up a chemical reaction by lowering (decreasing) the activation energy.

If you fill a glass to the brim with ice water and the ice melts, what will happen?

The water will drop slightly as the ice melts. One interesting property of water is that it achieves maximum density as a liquid, not as a solid. So, ice is less dense than water and floats. When it melts, it becomes more dense. More mass per unit volume means the level of the liquid drops slightly.