Which of these are made up of matter? Check all that apply.

parts of outer space where there is no air or atoms

salt dissolved in water

air in the lower levels of the Earth's atmosphere

leather made from cow hides

metal after if has been molded

A resonance structure is one of two or more Lewis structures for a single molecule, unable to be represented by a single Lewis structure true or false?

Naturally occuring boron is 80.20% boron-11 (atomic mass 11.01 amu) and 19.80% of some other isotope. What must the atomic mass of this second isotope be in order to account for the 10.81 amu average atomic mass of boron?.

Which of these is produced when fossil fuels are burned? A) oxygen Eliminate B) nitrogen C) hydrogen D) carbon dioxide

1. A student performs a reaction in a beaker by reaction silver nitrate with one long copper wire. The student's thermometer changes from 27°C to 35°C. Based on this, is this reaction endothermic, exothermic, or neither? Explain your reasoning. 2.

Did dinosaurs and humans ever exist at the same time?

What defines a material as being a mixture?

What do igneous rocks form from? (20pts!)

A gas at STP has a volume of 1.0 liter. If the pressure is doubled and the temperature remains constant, the new volume of the gas will be ... ?

Combustion analysis of toluene, a common organic solvent, gives 8.20 mg of co2 and 1.92 mg of h2o. if the compound contains only carbon and hydrogen, what is its empirical formula?

Why does the moon have phases? What are the four main phases of the moon? How long does it take to change from one to another?