Answer:
That the isotope H-1 is the most abundant in nature.
Explanation:
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In this case, since the average atomic mass of an element is computed considering the mass of each isotope and the percent abundance each, for hydrogen we would set up something like this:

Moreover, since the isotope notation H-1 and H-2 means that the atomic mass of H-1 is 1 amu, that of H-2 is 2 amu and the average one is 1.0079 amu, we can infer that the most of the hydrogen in nature is H-1 as the most of it composes the average hydrogen atom.
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Sorry this will probably be pretty long.
So think of the "control" as being something you yourself add to increase or decrease the effects in an experiment.
I'll give you an example so it is not as confusing.
Say you have decided to make an experiment on plants. Which plant can grow the fastest on which type of liquid? What is being added to this experiment? The liquid! Or all of the liquids you used. Like if you used Coke, Lime Gatorade, Orange Gatorade, and Water. Each drink will EFFECT each plant differently.
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They are kind of opposite processes. Chemical synthesis is execution of chemical reactions to make products. Like you take two substances, you put them together, they react and you have new a substance. For example.

here Sodium and Chlorine react to make a new substance which is Sodium Chloride.
Chemical decomposition is process of seperating a substance to different substances. There is a substance by a reaction this substance becomes two substances, Like : XY -> X+Y For example :
Answer:
The correct answer is: Ka= 5.0 x 10⁻⁶
Explanation:
The ionization of a weak monoprotic acid HA is given by the following equilibrium: HA ⇄ H⁺ + A⁻. At the beginning (t= 0) we have 0.200 M of HA. Then, a certain amount (x) is dissociated into H⁺ and A⁻, as is detailed in the following table:
HA ⇄ H⁺ + A⁻
t= 0 0.200 M 0 0
t -x x x
t= eq 0.200M -x x x
At equilibrium, we have the following ionization constant expression (Ka):
Ka= ![\frac{ [H^{+}] [A^{-} ]}{ [HA]}](https://tex.z-dn.net/?f=%5Cfrac%7B%20%5BH%5E%7B%2B%7D%5D%20%20%5BA%5E%7B-%7D%20%5D%7D%7B%20%5BHA%5D%7D)
Ka= 
Ka= 
From the definition of pH, we know that:
pH= - log [H⁺]
In this case, [H⁺]= x, so:
pH= -log x
3.0= -log x
⇒x = 10⁻³
We introduce the value of x (10⁻³) in the previous expression and then we can calculate the ionization constant Ka as follows:
Ka=
=
= 5.025 x 10⁻⁶= 5.0 x 10⁻⁶
Elements are substances that are made up of the same atoms which are capable of taking part in a chemical reaction.
There are different types of elements which are represented by symbols gotten from the first letter or the first and any other letter in the name of the element.
Examples of elements include:
When two or more of these elements combine together through a chemical bond, it leads to the formation of compounds.
Example of a compound includes:
- NaCl: The element sodium combine, through electrochemical bonding, with another element chlorine to form the compound sodium chloride.
Learn more here:
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