294 g of potassium dichromate contains 52 g of chromium and 39 g of potassium. what is the mass percent of oxygen in the compound?

Determine the empirical formula for succinic acid that is composed of 40.60% carbon, 5.18% hydrogen, and 54.22% oxygen.

Which of the following is an example of physical change not a chemical change? a) a log gives off heat and light as it burns. b) a tree stores energy from the sun in its fruit. c) a penny lost in the grass slowly changes color. d) a water pipe freezes and cracks on a cold night.

Helium decays to form lithium. which equation correctly describes this decay?