Answer:
Isotopes are basically atoms of an element that have an unequal number of neutrons and protons. Of course the proton number remains the same, but the neutron number either decreases or increases, which leads to an overall change in mass. However, no chemical properties of the atom/element are changed as the electrons are the same number and do not react. In regards to Helium 4, the original number of neutrons in Helium is 2, and protons 2 as well. We see an equal number of neutrons and protons, hence an unchanged mass, and the element is <em>not</em> an isotope.
Explanation:
The reaction equation will be as follows.

Hence, the expression for
is as follows.
![K_{a} = \frac{[H_{2}SO^{-}_{4}][H^{+}]}{[H_{3}AsO_{4}]}](https://tex.z-dn.net/?f=K_%7Ba%7D%20%3D%20%5Cfrac%7B%5BH_%7B2%7DSO%5E%7B-%7D_%7B4%7D%5D%5BH%5E%7B%2B%7D%5D%7D%7B%5BH_%7B3%7DAsO_%7B4%7D%5D%7D)
Let us assume that the concentration of both
and
is x.

x = 0.01118034
This means that the concentration of
is 0.01118034.
Since, we know that the relation between pH and concentration of hydrogen ions is as follows.
pH = ![-log [H^{+}]](https://tex.z-dn.net/?f=-log%20%5BH%5E%7B%2B%7D%5D)
= 
= 1.958
Thus, we can conclude that the pH of a 0.500 M solution of arsenic acid is 1.958.
If there is NO wind resistance, just plain math, this is the answer.
To get the answer you would divide 800 by 650.
800/650 = 1.230769231 (exactly)
That would translate to exactly <span>1 hour 13 minutes and 50 seconds </span>
The Rutherford experiment proved the Thomson “plum-pudding” model of the atom to be essentially correct did not give the results described and is denoted as option A.
<h3>What is Thomson “plum-pudding” model?</h3>
This model was proposed by J.J Thomson in which referred an atom as a sphere of positive charge, and negatively charged electrons are embedded in it to balance the total positive charge.
This model was incorrect and the Rutherford atomic model was adopted in which he described the electrons orbits about a tiny positive nucleus.
The nucleus contains protons and neutrons instead thereby making it the correct choice.
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The options include the following:
a.The Rutherford experiment proved the Thomson “plum-pudding” model of the atom to be essentially correct.
b.The Rutherford experiment was useful in determining the nuclear charge on the atom.
c.Milikan’s oil-drop experiment showed that the charge on any particle was a simple multiple of the charge on the electron.
d.The electric discharge tube proved that electrons have a negative charge