Is phosphorous an atom, element, or compound

When a septic tank backs up a goes in to clean it out

The number of moles of a given mass of a substance can be found without knowing its molecular formula or molar mass. true false

Astudent pours 10.0 g of salt into a container of water and observes the amount of time it takes for the salt to dissolve. she then repeats the process using the same amounts of salt and water but this time she slowly stirs the mixture while it is dissolving. the student performs the experiment one more time but this time she stirs the mixture rapidly. the dependent variable in this experiment is: time for salt to dissolve speed of stirring amount of water mass of salt