How do you know if a chemical change has taken place?

I want to balance Fe2so4+H20

Which statement summarizes the difference between a law and a theory? A. A theory is a conclusion that is drawn from observations and experiments, but a law provides an explanation. B.

Zn (s) + 2HCl (aq) - > ZnCl2 (aq) + H2 (g) Which half reaction correctly describes the oxidation that is taking place?

Which one of the following supports the hypothesis that life has changed over time? A.) Prokaryotes has no nucleus B.) Fossils are distinct from rock layer to rock layer C.) Some fossils plants have deep roots D.) The cell has no membrane

The 3 in 4p3 represents: a. third energy level b. the number of electrons c. period 3 d. the third sub level e. Li

Andy has two samples of liquids. Sample A has pH of 4, and sample B has a pH of 6. what can Andy conclude about these two samples? Sample A is a neutral b alkali c acidic Sample B is a neutral b alkali c acidic

How does a lone pair contribute to molecular shape? A. It is too small to affect the molecule's shape. B. It takes up space like an "invisible" atom. C. It forces the molecule into a tetrahedral shape. D. It lets the bonding pairs spread out more.

The are of a rectangle is 12 in^2. what is the area in cm^2. there are 2.54cm in an inch.

Which statements describe advantages of models? Check all that apply. Models make it possible to easily notice patterns. Models can be used to communicate and test design ideas. Models allow scientists to predict relationships.

Are energy levels and orbitals the same thing?