Which statement describes a way in which a mole is useful

A

Explanation:

A mole in chemistry is defined as the number or quantity of a chemical substance that consists of as many fundamental entities such as atoms, molecules, and ions. Therefore, the statement that best describes a mole is that, it is used for directly comparing the amounts of substances.

Explanation:

I found this hope it helps!! (read and try your best)

astronomers such as edwin hubble.

"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"