Silver nitrate (aq) + sodium chloride (aq) → silver chloride (s) + sodium nitrate (aq) AgNO3 (aq) + NaCl (aq) → AgCl (s) + NaNO3 (aq)

in the above reaction, why do the silver ions form a new compound with the chloride ions but not with the sodium ions?

"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"

it's c (engineer's do their work with mechanical stuff not on any living being)