The chemical reaction is written as:
2Zn + O2 = 2ZnO
We are given the amount of the product to be produced from the reaction. We use this value and the relation of the substances in the reaction to calculate what is asked. We do as follows:
2.10 g ZnO ( 1 mol / 81.408 g ) ( 1 mol O2 / 2 mol ZnO ) ( 32 g / 1 mol ) = 0.414 g O2 is needed
Answer:
Scientists were unsure about the last common ancestor between apes and humans because fossils are so scarce, researchers do not know what the last common ancestors of living apes and humans looked like or where they originated.
Explanation: