Pleae !

which of the following is a property of a pure substance? (5 points)

1. it consists of different types of compounds.
2. it may have substances in different states of matter.
3. the ratio of the particles that make it up is fixed.
4. its components can be separated by employing physical methods.

What volume of a 2.00 m stock solution of naoh is needed to prepare 150. ml of 0.40 m solution?

8) a mixture of he, ne and ar has a pressure of 7.85 atm. if the ne has a mole fraction of 0.47 and 8) ar has a mole fraction of 0.23, what is the pressure of he? a) 4.2 atm b) 3.7 atm c) 5.5 atm d) 2.4 atm e) 1.8 atm

Which of your 24 wells had indications that a chemical reaction occurred? how were you able to tell that a chemical reaction occurred? which of your 24 wells had indications that a physical reaction occurred? how were you able to tell that a physical reaction occurred? report on both mixing and evaporation. make a general statement about whether your hypotheses were validated or rejected. must your hypotheses be correct for this to be a successful laboratory?