Answer: Molarity of
anions in the chemist's solution is 0.0104 M
Explanation:
Molarity : It is defined as the number of moles of solute present per liter of the solution.
Formula used :

where,
n= moles of solute
= volume of solution in ml = 100 ml
Now put all the given values in the formula of molarity, we get

Therefore, the molarity of solution will be 

As 1 mole of
gives 2 moles of 
Thus
moles of
gives =
Thus the molarity of
anions in the chemist's solution is 0.0104 M
The given above pretty much states already that with the presence of the calcium carbonate which acts as the buffer will allow the solution to withstand changes in acidity. The greater the amount, the higher chances that it will be able to withstand the said changes. Therefore, if Lake X had greater ppm of CaCO3 then, it will be able to withstand greater amount of acid rain.