How does the density of a 4-g sample of copper compare to that of a 12-g sample of copper?

Which term refers to a property that depends only on the amount of a substance? ©@

How do you know when a chemical reaction has occurred

For the reaction c6h14(g) & longrightarrow; c6h6(g) + 4h2(g), δp(h2)/δt was found to be 2.5 x 10-2 atm/s, where δp(h2) is the change in pressure of hydrogen. determine δp(c6h14)/δt for this reaction at the same time.