Answer
a) decreased
b) I
Work Step by Step
(a) We know that the aluminum ball has a greater coefficient of thermal expansion as compared to that of the brass hole. Thus, it would contract by a greater amount if these two materials are cooled to the same temperature. Thus, the temperature of the system should be decreased so that the aluminum ball can fit in the brass plate hole.
(b) The correct option is (I) -- that is, the aluminum ball changes its diameter more with temperature than the brass plate, and therefore the temperature should be decreased.
