Dumbledore is pleased with your progress. Snape is, as always, somewhat indifferent. However, they both feel a gas phase density problem should come next. Calculate the density of
helium gas at 25.0◦C and at a pressure of 1521 mmHg. Express your answer in g/L.

In the 1800s, one of the statements in john dalton's atomic theory was that atoms are indivisible. later experimental evidence led to the discovery of subatomic particles such as neutrons, electrons, and protons. what happened to the indivisible atom part of dalton's atomic theory, and why?

Which of the following is an indication that a substance has undergone a chemical change? a. no new product has been formed. b. the color of the substance has not changed. c. the original constitute has not changed. d. the molecular structure has changed.

Describe the forces both attractive and repulsive that occur as two atoms move closer together.