Elias stretches a rubber band and lets it go. the rubber band flies across the room. elias says this demonstrates the transformation of kinetic energy to elastic potential energy. is elias correct?

No, he is not.

Explanation:

When he let the rubber band go, the band compresses, so there's elastic potential energy in it, which will be transformed into kinetic energy when it gains velocity and flies across the room.

Then, Elias had inverted the concepts: the experiment demonstrates the transformation of elastic potential energy to kinetic energy.

"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"

l dont know l am s sorry