A 25.0-gram sample of magnesium oxide contains 10.8 grams of magnesium. What is the percent of oxygen by mass in this compound?
(2 points)
a. 89.2 %
C. 43.2%
b. 14.2 %
d. 56.8 %

For which one of the following reactions is the value of δh° rxn equal to δh° f for the product? a. 2 h2 (g) + o2 (g) → 2 h2o (l) b. n2 (g) + o2 (g) → 2 no (g) c. 2 h2 (g) + o2 (g) → 2 h2o (g) d. h2o (l) + 1/2 o2 (g) → h2o2 (l) e. none of the above

Draw the lewis dot structure for each of the following polyatomic ions

Which states of matter have particles that move independently of one another with very little attraction?