The final charge on each of the three separated spheres in part (b) is +3.0 μc. how many electrons would have to be added to one of these spheres to make it electrically neutral?

electrons should be added to one of these spheres to make it electrically neutral.

Explanation:

Total charge on each sphere =  +3.0 μC =

In order to neutralize the positive charge equal magnitude of negative charge is to be added.

Total charge electrons, Q=  -3.0 μC =

Number of electrons = n

Charge on a single electron, e =

Q = n × e

electrons should be added to one of these spheres to make it electrically neutral.

"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"