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 %

Which statement describes how phase changes can be diagrammed as a substance is heated? the phase is on the y-axis and the temperature is on the x-axis. the temperature is on the y-axis and the phase is on the x-axis. the time is on the y-axis and the temperature is on the x-axis. the temperature is on the y-axis and the time is on the x-axis.

Which statement best describes the relationship between period and frequency of light waves? a) in wave b the period increases and the frequency decreases from wave a. b) in wave a the period increases and the frequency decreases from wave b. c) in wave b the period is shorter and the frequency is greater than in wave a. d) in wave a the period is shorter and the frequency is greater than in wave b.

The formation of a solid, also known as a is an indication of a chemical change. precipitate particulate particle powder