0. placer deposits form when (1 point)

hot, metal-rich fluids cool underground
heavy eroded particles settle out of moving water
organic matter is compressed over millions of years
magma cools in underground chambers

21. which of the following is a nonmetallic mineral resource? (1 point)

wood
coal
iron
aggregate

Awelder using a tank of volume 7.50×10^-2 m^3 fills it with oxygen (with a molar mass of 32.0 g/mol ) at a gauge pressure of 3.30×10^5 pa and temperature of 37.1 ∘c. the tank has a small leak, and in time some of the oxygen leaks out. on a day when the temperature is 23.1 ∘c, the gauge pressure of the oxygen in the tank is 2.00×10^5 pa . a) find the initial mass of oxygen. b) find the mass of oxygen that has leaked out.