1. An object submerged in water, rises up a volume of water equal to the volume of the object.
2. 1 milliliter of water has a volume of 1 cubic centimeters.
3. Mass= Density * Volume
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The water level rises from 20.mL to 41.mL means that a volume of 21mL of water has been displaced.
This means that the volume of the object is 21 cm cubed. (by 1 and 2)
By 3, the density of the piece of metal is:
Density=Mass/Volume=140 g / 21 cm^3= (140/21) g/cm^3=6.67 g/cm^3
Answer: 6.67 g/cm^3