What causes a spring to bounce up when it is pushed down and then released?
(a) Pushing the spring down gives it stored mechanical energy that turns into motion (b)The stored chemical energy in the spring turns into motion. (c) The chemical energy in the spring makes it move and bounce up. (d) Pushing the spring downturns chemical energy into mechanical energy.

(a) Pushing the spring down gives it stored mechanical energy that turns into motion

Explanation:

Pushing on the spring causes the mechanical energy, of pushing on the spring, to be stored in the spring through potential elastic energy. Due to the elasticity of the spring, when the spring is released and resumes its initial shape the stored energy is released and can be used to do work such as motion.

"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"