Answer:
The pH of the solution is 5.31.
Explanation:
Let "
is the dissociation of weak acid - HCN.
The dissociation reaction of HCN is as follows.

Initial C 0 0
Equilibrium c(1-
) c
c
Dissociation constant = 

In this case weak acids
is very small so, (1-
) is taken as 1.


From the given the concentration = 0.050 M
Substitute the given value.

![[H_{3}O^{+}]=c\alpha](https://tex.z-dn.net/?f=%5BH_%7B3%7DO%5E%7B%2B%7D%5D%3Dc%5Calpha)
![[H_{3}O^{+}]=0.05\times 9.8\times 10^{-4}= 4.9\times10^{-6}](https://tex.z-dn.net/?f=%5BH_%7B3%7DO%5E%7B%2B%7D%5D%3D0.05%5Ctimes%209.8%5Ctimes%2010%5E%7B-4%7D%3D%204.9%5Ctimes10%5E%7B-6%7D)
![pH= -log[H_{3}O^{+}]](https://tex.z-dn.net/?f=pH%3D%20-log%5BH_%7B3%7DO%5E%7B%2B%7D%5D)
![=-log[4.9\times10^{-6}]](https://tex.z-dn.net/?f=%3D-log%5B4.9%5Ctimes10%5E%7B-6%7D%5D)

Therefore, The pH of the solution is 5.31.
The qualities of a good hypothesis are: 1) Logically consistent with other theories and data 2) Have explanatory power 3) Be empirically testable 4) Similar hypothesis is the better hypothesis.
Answer: An atom that has gained an electron.
Explanation:
The number of protons in an atom cannot change except for some exceptional circumstances.
Cations (or metal ions) are formed when atoms lose electrons, as they want to form a complete outer electron shell to become as stable as possible.
For example, potassium is a 1+ ion, because it has one electron in its outer shell (and in group one). Therefore, to become more stable that electron is lost to become an ion or cation. As one electron is lost, the potassium cation charge is 1+ as the charge of an electron is 1-.
Answer:
The correct answer is a hypothesis.