Asample of pure calcium fluoride with a mass of 15.0 g contains 7.70 g of calcium. how much calcium is contained in 40.0 g of calcium fluoride?

20.53 g.

Explanation:

Using cross multiplication:

15.0 g of pure calcium fluoride contains → 7.70 g of calcium.

40.0 g of pure calcium fluoride contains → ??? g of calcium.

∴ The mass of Ca in 40.0 g of calcium fluoride = (7.70 g)(40.0 g)/(15.0 g) = 20.53 g.

the answer to your question is c.

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