How many liters of O2 would be needed to produce 5.75 moles of K₂O?​

A2.5% (by mass) solution concentration signifies that there is a 2.5 % (by mass) solution concentration signifies that there is blank of solute in every 100 g of solution. of solute in every 100 g of solution

What the blanks in these lines are ?

The activation energy for a(n) is quite large and usually takes extra energy from the environment, it is normally not a natural spontaneous process. combustion reaction endothermic reaction exothermic reaction catalyzed reaction