Barrons SAT Subject Test Chemistry, 13th Edition

67. (D) In 1 mol of Al 2 (CO 3 ) 3 , nine oxygens (three carbonates with three oxygen

atoms each) are in each formula unit, or 9 mol of O atoms are in 1 mol of

Al 2 (CO 3 ) 3. Because only 0.50 mol is given, there are (9) or 4.5 mol of O

atoms. In 4.5 mol of oxygen, there are

27.0 × 10^23 atoms or 2.7 × 10^24 atoms.