-20.16 KJ of heat are released by the reaction of 25.0 g of Na2O2.
Explanation:
Given:
mass of Na2O2 = 25 grams
atomic mass of Na2O2 = 78 gram/mole
number of mole = 
= 
=0. 32 moles
The balanced equation for the reaction:
2 Na2O2(s) + 2 H2O(l) → 4 NaOH(aq) + O2(g) ∆Hο = −126 kJ
It can be seen that 126 KJ of energy is released when 2 moles of Na2O2 undergoes reaction.
similarly 0.3 moles of Na2O2 on reaction would give:
= 
x = 
= -20.16 KJ
Thus, - 20.16 KJ of energy will be released.
shared to form an ionic bond.
I hope this helps!

As depth increases, the density of the layers decreases.
Answer:
0.1 M
Explanation:
The following data were obtained from the question:
Initial volume (V1) = 100 mL
Initial concentration (C1) = 0.5 M
Final volume (V2) = 500 mL
Final concentration (C2) =?
Using the dilution formula C1V1 = C2V2, the new concentration of the solution can be obtained as follow:
C1V1 = C2V2
0.5 × 100 = C2 × 500
50 = C2 × 500
Divide both side by 500
C2 = 50/500
C2 = 0.1 M
Therefore, the new concentration of the solution is 0.1 M