ASAP will give brainliest <3
1. What is the calculated empirical formula of the copper oxide if a 0.626 g sample of the copper oxide was reduced to 0.500 g of copper metal by heating in a stream of hydrogen gas?
2. If a sample of salt water has a measured concentration of 21.0 ppt, how many grams of salt are there in a 2.05 kg sample of this salt water?

Which of the following observations indicates that there is a small, dense, positively charged part in the center of an atom? some uncharged particles are scattered by a gold foil. all uncharged particles are attracted towards a gold foil. all positively charged particles pass straight through a gold foil. some positively charged particles bounce back from a gold foil.

Which statement best describes the flow of energy in this scenario

Using this reversible reaction, answer the questions below: n2o4 2no2 (colorless) (reddish-brown) -as the temperature increased, what happened to the n2o4 concentration? -was the formation of reactants or products favored by the addition of heat? -which reaction is exothermic? right to left or left to right? -if the change of enthalpy of this reaction when proceeding left to right is 14 kcal, which chemical equation is correct? n2o4 2no2 + 14 kcal n2o4 2no2, hr = +14 kcal n2o4 + 14 kcal 2no2 n2o4 2no2, hr = -14 kcal