Were any scientific investigations conducted for proposing the theory? Was this theory tested or simply expected?

Yes

Explanation:

Scientific theory can be defined as the solutions to the problems of the queries related to natural phenomena or it is the explanation for different aspects of the natural world. It is done with repeated testing procedure. To prove the facts of the theory, repeated experimental tests, and observations are done. The theories are tested under the controlled conditions of the experimental set up.

On the basis of the above description, we can say that the scientific investigations are done in the form of experimentation trials before proposing  a theory. The theory is tested and is not simply expected.

? you expect us to answer this? ? this is your schoolwork, i don't think we can with this, i think it would considering being

"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"