True or False: All compounds are made up of elements.

If 7 g of nitrogen reacts with 16 g of oxygen to form nitrogen dioxide (NO2), what is the total mass of the nitrogen dioxide produced?

In a chemical reaction, if the mass of the reactants is 75 g, what must be the mass of the products?

A compound has a total mass of 180 g, with 54 g of aluminum. What is the % by mass of aluminum in this compound?

If a compound is made up of 12 g of magnesium and 19 g of fluorine, what is the total mass of the compound?

If an element has an atomic number of 12 and an atomic mass of 24, how many protons does it have?

In methane (CH₄), what is the ratio of carbon atoms to hydrogen atoms?

An element consists of only one type of atom, while a compound is made up of atoms of two or more elements chemically bonded. True or False?

In a chemical reaction, 12 g of carbon reacts with 32 g of oxygen to produce 44 g of carbon dioxide. Does this observation support the law of conservation of mass?

The mass of the products must be exactly equal to the mass of the reactants because mass is conserved in a chemical reaction.

How many neutrons are present in an atom with atomic mass 39 and atomic number 19?

What is the ratio of nitrogen to hydrogen in ammonia (NH₃)?

Samples of gases containing nitrogen and oxygen were decomposed by electricity and the volume of each gas  produced was measured. Based on these results, which  is the correct chemical formula for Sample 2?

Bonus: Under certain conditions, 100 g of copper reacts with 25 g of oxygen to produce a compound. Under different conditions, 200 g of copper reacts with 25 g of oxygen to produce a different compound.  Which law does this example illustrate?