retard
...1982 penny)(X)]+[(mass of post 1982 penny)(10-X)] 27.379=[(3.078)(X)]+[(2.489)(10-X)] 27.379=3.078X+24.89-2.489X 27.379=0.589X+24.82 -24.82 2.489=0.589X 2.489/0.589 X=4 Therefore there are 4 pre 1982 pennies and 6 post 1982 pennies. Percent abundance of the 2 isotopes of the element Pennyum % of pre 1982 Pennyum = # of pre 1982 x 100% 10 % = 4/10 x 100% 40% of the pennies were pre 1982. % of post 1982 Pennyum = 100 – (% of pre 1982 Pennyum) % = 100-40 605 of the pennies were post 1982. Average atomic mass of Pennyum 40% becomes 0.40 60% becomes 0.60 Average atomic mass = [(decimal abund. pre 1982)(mass pre 1982] + [(decimal abund. post 1982)(mass post 1982)] Average atomic mass = [0.40(3.078)]+[0.60(2.489)] Average atomic mass = 1.231+1.492 Average atomic mass = 2.724 Part B. Questions: 1. What was “tricky” about settling on the alloy to be used for the coin? 2. Why make a dollar coin? (list at least two reasons) 3. Of what elements is the “golden dollar” composed? 4. What is the percent composition of each element in the “golden dollar”? 5. (a) What was the problematic issue involving conductivity? (b) Which metal was used to overcome the conductivity issue? (c) Why was this particular meta...