Context: The relative reactivity of zinc and its ability to attract oxidation to itself makes it an efficient sacrificial anode in cathodic protection (CP). For example, cathodic protection of a buried pipeline can be achieved by connecting anodes made from zinc to the pipe. Zinc acts as the anode (negative terminus) by slowly corroding away as it passes electric current to the steel pipeline.[note 2] Zinc is also used to cathodically protect metals that are exposed to sea water from corrosion. A zinc disc attached to a ship's iron rudder will slowly corrode, whereas the rudder stays unattacked. Other similar uses include a plug of zinc attached to a propeller or the metal protective guard for the keel of the ship.

Question: What makes zinc an efficient sacrificial anode?
Answer: relative reactivity of zinc and its ability to attract oxidation

Question: Connecting anodes made from zinc to buried pipe creates what?
Answer: cathodic protection

Question: What does attaching a zinc disc to a ships iron rudder do?
Answer: protect metals that are exposed to sea water from corrosion

Question: Why does zinc protect metals exposed to sea water from corroding?
Answer: will slowly corrode, whereas the rudder stays unattacked

Question: What makes zinc an inefficient sacrificial anode?
Answer: Unanswerable

Question: What does attaching a zinc sphere to a ship's iron rudder not help with?
Answer: Unanswerable

Question: Why is zinc not able to ever corrode?
Answer: Unanswerable

Question: Why does zinc harm metals exposed to sea water?
Answer: Unanswerable