Ten name if this compound is Potassium Oxide
Answer:
Selenium
Explanation:
Oxygen is present in the group sixteen.
This group consist of oxygen, sulfur, selenium, tellurium and polonium.
All of these have same number of valance electrons thus they show similar properties.
From the given list of elements only selenium is belong to oxygen family thus it has properties similar to the oxygen.
Electronic configuration of oxygen:
O = [He] 2s² 2p⁴
Electronic configuration of selenium:
Se = [Ar] 3d¹⁰ 4s² 4p⁴
While aluminium, boron and phosphorus are belongs to other groups that's why their properties are not similar to the phosphorus.
phosphorus is present in group 15.
Boron and aluminium are present in group 13.
Every isotope of an element has a different number of neutrons, which means that the atomic property which is different in each isotope of an element is mass number.
Mass number depends on the number of neutrons in an element.
The concentration of the hydronium ion in hydrochloric acid is 0.0045 M, and the pH of the solution is 2.34.
<h3>What is pH?</h3>
pH is the potential of the hydrogen or the hydronium ions in the aqueous solution.
As the solution contains 
HCl the concentration of the hydronium ion will be the same, 
The pH of the solution is calculated as:
![\begin{aligned} \rm pH &= \rm -log[H^{+}]\\\\&= - \rm log (4.5 \times 10^{-3})\\\\&= 2.34\end{aligned}](https://tex.z-dn.net/?f=%5Cbegin%7Baligned%7D%20%5Crm%20pH%20%26%3D%20%5Crm%20-log%5BH%5E%7B%2B%7D%5D%5C%5C%5C%5C%26%3D%20-%20%5Crm%20log%20%284.5%20%5Ctimes%2010%5E%7B-3%7D%29%5C%5C%5C%5C%26%3D%202.34%5Cend%7Baligned%7D)
The concentration of the hydroxide ion is calculated from pH and hydronium ion as:
![\begin{aligned} \rm [H_{3}O^{+}][OH^{-}] &= 10^{-14}\\\\&= \dfrac{1 \times 10^{-14}}{4.5 \times 10^{-3}}\\\\&= 2.2 \times 10^{12}\end{aligned}](https://tex.z-dn.net/?f=%5Cbegin%7Baligned%7D%20%5Crm%20%5BH_%7B3%7DO%5E%7B%2B%7D%5D%5BOH%5E%7B-%7D%5D%20%26%3D%2010%5E%7B-14%7D%5C%5C%5C%5C%26%3D%20%5Cdfrac%7B1%20%5Ctimes%2010%5E%7B-14%7D%7D%7B4.5%20%5Ctimes%2010%5E%7B-3%7D%7D%5C%5C%5C%5C%26%3D%202.2%20%5Ctimes%2010%5E%7B12%7D%5Cend%7Baligned%7D)
Now, for the calcium hydroxide solution, the calculations are shown as,
pOH is calculated as:
![\begin{aligned} \rm pOH &= 14- 8 = 6\\\\\rm [OH^{-}] &= \rm antilog (-6)\\\\&= 10^{-6} \end{aligned}](https://tex.z-dn.net/?f=%5Cbegin%7Baligned%7D%20%5Crm%20pOH%20%26%3D%2014-%208%20%3D%206%5C%5C%5C%5C%5Crm%20%5BOH%5E%7B-%7D%5D%20%26%3D%20%20%5Crm%20antilog%20%28-6%29%5C%5C%5C%5C%26%3D%2010%5E%7B-6%7D%20%5Cend%7Baligned%7D)
The concentration of calcium hydroxide is calculated as:
![\begin{aligned} &= \dfrac{1}{2} \times \rm [OH^{-}]\\\\&= 5 \times 10^{-4} \;\rm M\end{aligned}](https://tex.z-dn.net/?f=%5Cbegin%7Baligned%7D%20%26%3D%20%5Cdfrac%7B1%7D%7B2%7D%20%5Ctimes%20%5Crm%20%5BOH%5E%7B-%7D%5D%5C%5C%5C%5C%26%3D%205%20%5Ctimes%2010%5E%7B-4%7D%20%5C%3B%5Crm%20M%5Cend%7Baligned%7D)
Therefore, the pH and the pOH give the concentration of the hydrogen or the hydronium ion and the hydroxide ion.
Learn more about pH and pOH here:
brainly.com/question/16062632
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