Half of the subjects (the study volunteers) were given a placebo. The other half were given the vaccine. This created two groups: the placebo group and the vaccine group. The study used a random process to choose which subjects were assigned to each group. Why would subjects be randomly assigned to the groups?

How many grams of magnesium metal will react completely with 8.3 liters of 5.5 m hcl? show all of the work needed to solve this problem. mg (s) + 2hcl (aq) → mgcl2 (aq) + h2 (g)

Silver tarnishes as silver metal reacts with hydrogen sulfide, h2s, in the air. in this reaction, dark silver sulfide, au2s, covers the surface of silver. when silver is polished, this coating of silver sulfide can be removed from the surface. this makes the silver shiny again. enter the coefficients that balance the tarnishing reaction equation. (type 1 for no coefficient.)

Predict whether the changes in enthalpy, entropy, and free energy will be positive or negative for the boiling of water, and explain your predictions. how does temperature affect the spontaneity of this process?