Answer: Manholes are usually round, primarily because roundness is the best shape to resist the compression of the earth; covers are round because they are easier to manufacture than square or rectangular shapes, they are easier to move by rolling, and they can't fall into the opening.
Explanation:
Answer:
d. oxygen (O2) is the answer
Endocrine system im pretty sure
The moles of each element found in a 5.00 g nickel coin is calculated as below
moles =mass/molar mass
calculate the mass of each element =% composition of element/100 x total mass of nickel
Mn = 9/100 x5 = 0.45g
Cu=56/100 x5= 2.8 g
Ag= 35/100x5= 1.75 g
moles of each element is therefore=
Mn = 0.45g/54.94 = 8.19 x10^-3 moles
Ag=1.75g/107.87 g/mol = 0.0162 moles
Cu = 2.8 g/63.5 g/mol=0.0441 moles
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