A sample of calcium fluoride was decomposed into the constituent elements. If the sample produced 294 mg of calcium, how many g of fluorine were formed?​

Approximately of fluorine would be produced.

Explanation:

Look up the relative atomic mass of these calcium and fluorine on a modern periodic table:

In other words, the mass of each mole of calcium atoms is (approximately) . Similarly, the mass of each mole of fluorine atoms is (approximately) .

Calculate the number of moles of calcium atom that were produced:

.

Every formula unit of calcium fluoride, , contains twice as many fluorine atoms as calcium atoms.

Hence, if the sample contained approximately calcium atoms, it would contain twice as many fluorine atoms:

.

Calculate the mass of that many fluorine atoms:

.

"record the time to complete a chemical reaction" would most likely be part of a lab procedure.