Answer : The hydroxide ion concentration of a solution is, 
Explanation :
As we know that:
pH : It is defined as the negative logarithm of hydrogen ion concentration.
Mathematically,
![pH=-\log [H^+]](https://tex.z-dn.net/?f=pH%3D-%5Clog%20%5BH%5E%2B%5D)
Similarly,
pOH : It is defined as the negative logarithm of hydroxide ion concentration.
Mathematically,
![pOH=-\log [OH^-]](https://tex.z-dn.net/?f=pOH%3D-%5Clog%20%5BOH%5E-%5D)
Given:
pOH = 6.42
![6.42=-\log [OH^-]](https://tex.z-dn.net/?f=6.42%3D-%5Clog%20%5BOH%5E-%5D)
![[OH^-]=3.8\times 10^{-7}M](https://tex.z-dn.net/?f=%5BOH%5E-%5D%3D3.8%5Ctimes%2010%5E%7B-7%7DM)
Therefore, the hydroxide ion concentration of a solution is,
Voltage is known to be used as a requirement for stimulating an axon. The axon conducts electrical signals away from the nerve cell. The main function of the axons is that it is specifically used to transmit information, in a form of electrical impulse, to the other parts of the body.
Answer:
pH = 3.37
Explanation:
A weak acid as lactic acid in a solution with sodium lactate (Its conjugate base) produce a buffer. The pH of this buffer is obtained using H-H equation:
pH = pKa + log [A-] / [HA]
<em>Where pH is the pH of the buffer,</em>
<em>pKa is 3.86</em>
<em>And [] could be taken as the moles of A- = Sodium lactate and HA = Lactic acid.</em>
<em />
Moles A-:
40.0mL = 0.0400L * (0.75mol / L) = 0.030 moles A-
Moles HA:
75.0mL = 0.0750L * (1.25mol / L) = 0.09375 moles HA
Replacing:
pH = 3.86+ log [0.030 moles A-] / [0.09375 moles HA]
<h3>pH = 3.37</h3>
<em />
Dilution means adding more solvent to a solution to lower down its concentration and in that process volume of solution expands. That means on diluting a solution the following parameters will change:
1. Amount of solvent
2. Total volume of the solution
3.Concentration of the solution
So the parameter that does not change is the amount of solute that will remain constant on diluting a solution, So here the the answer will be the amount of solute that will remain unchanged during dilution.
C. A tree Trees can turn light into chemical energy using photosynthesis.
