Recycling!! And also planting more trees.
Hope this helps!
Answer:
C. To determine how efficient reactions are.
D. To determine how much reactant they need.
Explanation:
When you are doing a reaction, you are hoping for a percent yield to close of 100%. You make the reaction and determine how many product you obtain. If you know the percent yield of a reaction you can calculate the amount of reactant you need to obtain a determined amount of product.
Having this in mind:
A. To balance the reaction equation. false. To calculate percent yield you need to balance the reaction before. You don't use percent yield to balance the reaction
B. To determine how much product they will need. false. You determine how much product you obtain after the reaction. How much product you need is independent of percent yield
C. To determine how efficient reactions are. true. A way to determine efficience of a reaction is with percent yield. An efficient reaction has a high percent yield.
D. To determine how much reactant they need. true. If you know percent yield of a reaction you can know how many reactant you must add to obtain the amount of product you want.
Considering the definition of molarity, the molar concentration is 0.294 
.
Molarity reflects the concentration of a solution indicating the number of moles of solute that are dissolved in a given volume.
The molarity of a solution is calculated by dividing the moles of the solute by the volume of the solution:
Molarity is expressed in units .
In this case, you know:
- amount of moles of solute= 0.250 moles
- volume= 0.850 L
Replacing in the definition of molarity:
Solving:
molarity= 0.294
Finally, the molar concentration is 0.294 .
Learn more about molarity with this example: brainly.com/question/15406534?referrer=searchResults
H• •Be• •H --> H:Be:H
Since there are 4 valence electrons in total, Beryllium has 2 and Hydrogen has 2. You would put the Be in the middle because there is only 1 of them.
