Solving a chemistry problem

Solving a chemistry problem

5. A small amount of carbon dioxide was passed through an aqueous solution of sodium silicate to form a sol, the coagulation threshold of which with calcium bromide is equal to C mmol-eq/l. Estimate the coagulation threshold of this sol with cesium phosphate.
1) С/64 2) С*64 3) С/729 4) С*729

Additional information:

If you do not open the file - install the RAR archiver. Inside the archive you will find a solution in Word format.