is the potential energy of the ball as it is half way through the fall, 20 meters high
<u>Explanation:</u>
Given data:
Height of the fall = 20 m
Given that the body is half-way through the fall, it is at above the ground 10 m

We need to find its potential energy (P.E)
Energy due to the body’s position is referred as potential energy. It means the energy when body is at rest. It can be expressed as below,

Where
m – The body’s mass
g - Acceleration due to gravity 
h - Height of the body
By substituting the given values, we get

Since the mass is not provided, just kept it.
One difficulty encountered in precipitation titration is that it is hard to determine the exact end point of its reaction.
Precipitation titration is a titration in which a reaction occurs from the analyte and titrant to form an insoluble precipitate.
With the use of silver for the titrations, (argentometric) we are able to develop many precipitation reactions.
The precipitation titrimetry methods with the use of argentometry includes
• Mohr’s Method
• Fajan’s Method
• Volhard’s Method
Difficulties encountered in precipitation titration includes
- Getting the exact end point is hard.
- it is a very slow titration method.
- it includes periods of filtration and cooling thereby reducing the reactions available for this type of titration.
See more on Precipitation: brainly.com/question/20628792
So in one hour half the amount remains (that's what half life means). In two hours 1/4 (or half of half) would remain and in three hours 1/8 would remain.
So the answer is 1/8
The element "X" is "O" (oxygen).
<h3>Calculation:</h3>
Given,
Chemical formula = Na₂CX₃
Formula mass = 106 amu
Molar mass of Na = 23 amu
Molar mass of C = 12 amu
To find,
Element X =?
We will equate the equation as follows,
2(23) + 12 + 3(y) = 106
46 + 12 + 3y =106
58 + 3y = 106
3y = 106 - 58
3y = 48
y = 48/3
y = 16
We know that Oxygen has molecular mass of 16. Therefore the element "X" is "O".
Learn more about molar mass here:
brainly.com/question/22997914
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