What happens to a sheet of copper as the average kinetic energy of the copper molecules decreases? a. it melts. b. it expands.** c. it gets cooler. d. it gains energy.

Temperature is directly proportional to the average kinetic energy of the molecules.  

KE = 3/2 kT where KE is the average kinetic energy of a molecule and k is Boltzmann's constant (1.381x10^-23 J/K).  

KE = 3/2 RT where KE is the average kinetic energy for a mole of molecules and R is the gas constant (8.314 J/molK).  

Therefore, as KE decreases, T decreases and it gets cooler.

It gets cooler...as metal gains energy it becomes hotter and melts...

**The correct answer is C

It gets cooler.

Explanation:

I took the test.

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"