On what law is stoichiometry based? Why is it essential to use balanced equations in solving stoichiometric problems?

Consider the combustion of carbon monoxide. Starting with 3.60 moles of CO, what is the number of moles of CO$_2$ produced if there is enough oxygen gas to react with the entire CO?

$Calculate the molecular mass or formula mass (in u) of each of the following substances:\$$\mathrm{C}$_6 $\mathrm{H}$_6$.

Calculate the molecular mass or formula mass (in u) of each of the following substances:
$\mathrm{NaI}$.

$Calculate the molecular mass or formula mass (in u) of each of the following substances:\$$\mathrm{CH}$_4$.

Which of the following has a greater mass: two atoms of lead or

$$5.1\times10^{-23}$$

mole of helium?

Which of the following has more atoms: 1.10 g of hydrogen atoms or 14.7 g of chromium atoms?

A modern penny weighs $2.5 g$ but contains only $0.063 g$ of copper (Cu). How many copper atoms are present in a modern penny?

What is the mass in grams of a single atom of carbon?

What is the mass in grams of a single atom of each of the following elements? (a) Hg, (b) Ne.

How many grams of gold (Au) are there in 15.3 moles of Au?

How many moles of calcium (Ca) atoms are in 77.4 g of Ca?

How many moles of cobalt (Co) atoms are there in $6.00 X 10^9$ (6 billion) Co atoms?

How many atoms are there in 5.10 moles of sulfur (S)?