What does the plus mean next to an element

A sample of propane, c3h8, contains 15.7 moles of carbon atoms. how many total moles of atoms does the sample contain?

A cube has a depth of 10 cm. What is the volume of the cube? Or What is depth?

Which property or properties of life does water have?

The elements in the periodic table are arranged in order of increasing atomic mass increasing atomic number decreasing atomic number decreasing atomic mass

Different elements emit different emission spectra when they are excited because each type of element has a unique energy level systems. Each element has a different set of emission colors because they have:

What's the physical state of hydrogen and zinc in 2HCl+Zn=ZnCl2+H2

H2O (s) ⇒ H2O What would be the best argument against writing this in the form of a chemical equation?

What effect does an increase in products have on the reaction rate of a mixture at equilibrium?

Explain the basic principles of a distillation unit operation

How many valence electrons do the halogens possess?