A.
For Division 4.3, PG III is assigned when any substance would react slowly with water at ambient temperature such that the maximum rate of evolution of flammable gas is equal to or greater than 1 L/kg of substance per hour, and which does not meet the criteria of PG I or II. If a given substance gives off flammable gas when in contact with water at a rate of say 0.9L/kg of substance per hour, this will not be restricted. If it is 1L/kg of substance at less than 1 hour, certainly, it is already eligible as PG III but you must further check what is the evolution of flammable gas in 1 hour. If it is 20L/kg or more, you must assign the substance to PG II.