The metal which will get corroded at a slower rate on exposure to air and water is
Gold
The process of conversion of a metal into its compounds by continuous interaction with atmospheric air and water vapour is known as corrosion. This is an electrochemical reaction in which metals lose electrons and oxygen accepts them. Different metals react differently with oxygen. The arrangement of metals as per reactivity series is: K > Na > Ca > Mg > Al > Zn > Fe > Ni > Sn > Pb > H > Cu > Ag > Au. Gold, being the least reactive metal, will react with oxygen at a slower rate than sodium, potassium, and magnesium. Therefore, gold will undergo corrosion at a slower rate.