Why is it possible to use physical properties to separate a mixture

What pressure will be exerted by 0.675 moles of a gas at 25*c if it is in a 0.750-l container?

Suppose a lab group reports a ppercent yield of sand of 105. is it really possible to collect more sand than was originally represented? what is the possible explanation for the extra product?

What is the chemical name of the compound na2co3? use the list of polyatomic ions and the periodic table to you answer. a. sodium carbon oxide b. sodium carbonate c. sodium(ll) carbonate d. sodium oxalate