Answer:
Two half lives.
Explanation:
It is known that the decay of isotopes and radioactive material obeys first order kinetics.
Also, it is clear that in first order decay the half-life time is independent of the initial concentration.
That means for a sample 100% to decay to 50 % it will take one half-life, and to decay the remaining 50% to 25% it will take another half-life.
So, for a sample has 25% parent and 75% daughter it will have two half-lives.
Answer:
D: chain of volcanoes circling the Pacific Basin
Explanation:
The answer is
<span>Fe3+ + e- Fe2+ = 0.77 V</span>
2Ca + O2 = 2CaO
First, determine which is the excess reactant
72.5 g Ca (1 mol) =1.8089725036
(40.078 g)
65 g O2 (1 mol) =2.0313769611
(15.999g × 2)
Since the ratio of to O2 is 2:1 in the balanced reaction, divide Ca's molar mass by 2 to get 0.9044862518. this isn't necessary because Ca is already obviously the limiting reactant. therefore, O2 is the excess reactant.
Now do the stoichiometry
72.5 g Ca (1 mol Ca) (1 mol O2)
(40.078 g Ca)(2 mol Ca)(31.998g O2)
=0.0282669621 g of O2 left over
