Answer:
The answer will be :
In year 1869
Russian scientist named Dmitri Mendeleev
Chart called Mendeeleves periodic table
increasing atomic masses
physical and chemical properties.
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The weighted average of a penny is = 67.9g
<h3>Calculation of average weight</h3>
The sample of penny for pre 1982 is a total of = 18 pennies.
The mass of each penny for pre 1982 = 3.1
Therefore the total weight for penny for pre 1982
= 18×3.1
= 55.8
The sample of penny for post 1982 is a total of = 32 pennies.
The mass of each penny for post 1982 = 2.5
Therefore the total weight for penny for post 1982
=32×2.5
= 80
The weighted average
= 55.8+80/2
= 135.8/2
= 67.9g
learn more about mass here:
brainly.com/question/14156113
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First one. Coefficients are numbers that balance the equation, just like if there is an equation in math where 1=2, you need to multiply 1 by 2 to make that equation true. That's a nice jingle you can remember.