Sodium-22 remain : 1.13 g
<h3>Further explanation
</h3>
The atomic nucleus can experience decay into 2 particles or more due to the instability of its atomic nucleus.
Usually, radioactive elements have an unstable atomic nucleus.
General formulas used in decay:

T = duration of decay
t 1/2 = half-life
N₀ = the number of initial radioactive atoms
Nt = the number of radioactive atoms left after decaying during T time
half-life = t 1/2=2.6 years
T=15.6 years
No=72.5 g

Answer : The number of grams of solute in 500.0 mL of 0.189 M KOH is, 5.292 grams
Solution : Given,
Volume of solution = 500 ml
Molarity of KOH solution = 0.189 M
Molar mass of KOH = 56 g/mole
Formula used :

Now put all the given values in this formula, we get the mass of solute KOH.


Therefore, the number of grams of solute in 500.0 mL of 0.189 M KOH is, 5.292 grams
Answer:
pH = 2.32
Explanation:
H2A + H2O -------> H3O+ + HA-
Ka2 is very less so i am not considering that dissociation.
now Ka = 8.0×10−5
= [H3O+] [HA-] / [H2A]
lets concentration of H3O+ = X then above equation will be
8.0×10−5 = [X] [X] / [0.28 -X]
8.0×10−5 = X2 / [0.28 -X]
X2 + 8.0×10−5 X - 2.24 x 10−5
solve the quardratic equation
X =0.004693 M
pH = -log[H+}
= -log [0.004693]
= 2.3285
≅2.32
pH = 2.32