<u>Answer:</u> The balanced half reaction is written below.
<u>Explanation:</u>
Reduction reaction is defined as the chemical reaction in which an atom gains electrons. The oxidation number of the atom gets reduced during this reaction.

When oxygen gas is reduced to oxide ions, the number of electron transferred are 2
The chemical equation for the reduction of oxygen gas to oxide ions follows:

Hence, the balanced half reaction is written above.
The answer to that question would be Activation energy. If would like me to elaborate just let me know. :)
Absolutely nothing a neutron has a neutral charge
Answer: Option C) 9.5
Explanation:
Given that,
pOH of solution = ?
pH of solution = 4.5 (it is an acidic solution because any pH values less than 7.0 is said to be acidic)
Recall that pH is the negative logarithm of hydrogen ion concentration in the solution while pOH is the negative logarithm of hydroxide ion concentration in the solution.
Hence, pH + pOH = 14
4.5 + pOH = 14
pOH = 14 - 4.5
pOH = 9.5
Thus, the pOH of the same solution is 9.5
Question 17
The subscript 2 is the atomic number for helium and subscript 4 is the mass number for Helium
<u><em>explanation</em></u>
when writing down an isotope of an element the mass number of that isotope is written in upper side of the chemical symbol, while atomic number is written on the lower side.
Since 4 is on upper side it is the mass number of He, while 2 is the atomic number since it is on lower side.
Question 18
The type of radiation emitted when polonium -212 form lead 208 is an alpha particle
<u><em>explanation</em></u>
Alpha decay is a decay in which an atomic nuclei emit an alpha particles and be transformed into different atomic nuclei with a mass number that is reduced by 4
polonium 212 is reduced by 4 to form lead 208 therefore it undergo alpha particle decay.