What type of substance is reactant A?

How many grams of naoh are needed to make 0.250 liter of a 0.500 m solution of naoh? 0.125 g 5.00 g 2.00 g

Which part of a feedback mechanism is able to monitor the conditions outside of cells and usually uses nerve cells to relay this information to an intergrating center

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?