True or false a change in temperature is always an indicator of a chemical reaction.

Identify the balanced chemical equation that represents a decomposition reaction. p4 + 3o2 ⟶ p2o3 2fe(oh)3 ⟶ 2feo3 + h2o cuso4 ⟶ cuo + 2so3 2fe(oh)3 ⟶ fe2o3 + 3h2o

Asample of the male sex hormone testosterone, c19h28o2, contains 3.88×10^21 atoms of hydrogen.(a) how many atoms of carbon does it contain? (b) how many molecules of testosterone does it contain? (c) how many moles of testosterone does it contain? (d) what is the mass of this sample in grams?

Asolution contains 225 g of sodium chloride, nacl, dissolved in enough water to make a 0.25 l of solution. what is the molarity of the solution?