This question involves the concepts of buoyant force and the weight of an object.
The buoyant force on the piece of metal is "8 N".
The apparent weight of the piece of metal is given by the following formula:
Apparent Weight = Actual Weight - Buoyant Force
Buoyant Force = Actual Weight - Apparent Weight
Buoyant Force = 20 N - 12 N
Buoyant Force = 8 N
Learn more about buoyant force here:
brainly.com/question/21990136?referrer=searchResults
The attached picture illustrates the buoyant force.