How many element are there on the periodic table?

Two solids are mixed in a flask and stirred. after a few minutes, the flask becomes cold. which of the following best describes this reaction? a. an exothermic reaction b. a combustion reaction c. an endothermic reaction d. a decomposition reaction

Which of the following is true regarding chemical and nuclear reactions?

For part 1, describe the changes in the colors of the well, if any, as you go from well 1 to well 9—that is, as you go from the well with the least copper(ii) nitrate to the well with the most copper(ii) nitrate. which wells had the most distinct precipitate? for part 2, describe the changes in the colors of the well, if any, as you go from well 1 to well 9—that is, as you go from the well with the least iron(ii) sulfate to the well with the most iron(ii) sulfate. which wells had the most distinct precipitate? for part 3, describe the changes in the colors of the well, if any, as you go from well 1 to well 9—that is, as you go from the well with the least iron(iii) nitrate to the well with the most iron(iii) nitrate. which wells had the most distinct precipitate?