GC Atomic Structure

How many grams of MgCO3 contain 24.00 g of oxygen? (The molar mass of MgCO3 is 84.30 g mol–1)

  1. 42.15 g
  2. 84.30 g
  3. 126.00 g
  4. 154.00 g

Answer

Mass of oxygen atom = 16 g

Mass of oxygen in 84.30 g of MgCO3 = 3 x 16 = 48 g

So, 24 g of oxygen will be in 42.15 g of MgCO3.

The correct option is A.