Answer the following- what is the dot structure, cross-cross method, molecular mass, compound name, compound formulae for each reactants:
potassium and oxygen,
sodium and sulfur,
calcium and nitrogen, carbon and sulfide, hydrogen and phosphorus?

What is a scientific theory? a. a scientist's guess about how something works b. the results of an experiment obtained using the scientific method c. a proven fact that will never change d. an idea that is backed by data from many sources

Write the empirical chemical formula of calcium with a mass percent of 38.8, phosphorus with a mass percent of 20.0, and oxygen with a mass percent of 41.3.

Agroup of students is studying convection current. they fill two identical balloons with the same amount of helium. one balloon is placed in a freezer and the other is in an area with warm air. after 10 minutes, the balloon are released from a height of 1 meter. which of the following to the students most likely observe? a) the warm balloon expands and rises. the cold balloon shrinks and sinks b) the balloon both rise. the cold balloon is larger than the warm balloon c) the cold balloon expands and rises. the warm balloon shrinks and sinks d) the balloon rise at the same rate. both balloons are the same size