What overall effect does adding a catalyst have on a heterogeneous chemical reaction

Which statement is true about this reaction? 14n+1h 15o it is a practical source of energy on earth. it occurs only outside the solar system. its product is heavier than each of its reactants. it shows the critical mass of an element.

The student repeated the experiment using a higher concentration of acid. the same volume of acid and the same mass of magnesium ribbon were used. what volume of hydrogen gas would have been produced after 60 seconds?

The following transition occurs at a molecular level for a substance. what transition corresponds to this change in microscopic structure? the carbon dioxide molecules on the left are in a regular, tightly packed pattern. after heating, it becomes much lower density. a. melting b. boiling c. sublimation d. freezing