Answer:
84.6 mL
Explanation:
To get the total volume of soultion we must add the given volumes together.
4.21 mL + 80.4 mL = 84.6 mL
The daughter nucleus that is produced is ₂₉⁶³cu.
What is Electron capture?
The process of drawing an electron to the nucleus, where it combines with a proton to create a neutron and a neutrino particle, is known as electron capture.
The daughter nucleus is the nucleus that is made by the parent nucleus. The nucleus that remains after the decay is called the daughter nucleus.
Here is the chemical formula for the reaction that results in the electron capture of the zinc-63 nucleus:


Thus, the daughter nucleus produced when zn63 undergoes electron capture is
.
To learn more about Electron capture, refer to the below link:
brainly.com/question/10964824
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Answer : The value of acid dissociation constant is, 
Solution : Given,
Concentration pyridinecarboxylic acid = 0.78 M
pH = 2.53
First we have to calculate the hydrogen ion concentration.
![pH=-\log [H^+]](https://tex.z-dn.net/?f=pH%3D-%5Clog%20%5BH%5E%2B%5D)
![2.53=-\log [H^+]](https://tex.z-dn.net/?f=2.53%3D-%5Clog%20%5BH%5E%2B%5D)
![[H^+]=2.95\times 106{-3}M](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%3D2.95%5Ctimes%20106%7B-3%7DM)
Now we have to calculate the acid dissociation constant.
The equilibrium reaction for dissociation of (weak acid) is,

initially conc. 0.78 0 0
At eqm. (0.78-x) x x
The expression of acid dissociation constant for acid is:
![k_a=\frac{[C_6H_4NO_2^-][H^+]}{[C_6H_4NO_2]}](https://tex.z-dn.net/?f=k_a%3D%5Cfrac%7B%5BC_6H_4NO_2%5E-%5D%5BH%5E%2B%5D%7D%7B%5BC_6H_4NO_2%5D%7D)
As, ![[H^+]=[C_6H_4NO_2^-]=x](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%3D%5BC_6H_4NO_2%5E-%5D%3Dx)
So, 
Now put all the given values in this formula ,we get:



Therefore, the value of acid dissociation constant is, 
Answer:
0.258 mg of iron remains.
Explanation:
To solve this problem we can use the formula
M₂ = M₀ * 
Where M₂ is the mass remaining, M₀ is the initial mass, and t is time in days.
Using the data given by the problem:
M₂ = 2.000 mg * 
M₂ = 0.258 mg