Refrigerants
Families, names and numbers
The exam expects you to place a refrigerant in its family from its number. R-22 (CHClF2) is an HCFC; R-134a, R-32 and R-410A are HFCs; R-290 (propane) and R-600a (isobutane) are hydrocarbons of safety class A3; R-717 is ammonia; R-744 is carbon dioxide. R-410A is a near-azeotropic 50/50 blend of R-32 and R-125 with a very small glide, whereas R-407C is zeotropic with a glide of about 5 K, so its liquid and vapour temperatures differ at the same pressure.
Oil and charging
CFC and HCFC plants use mineral oil; HFCs need polyolester (POE) or PAG, which absorb moisture quickly and must never be left open to air. Blends must be charged as liquid from the cylinder - vapour charging fractionates the mixture and changes composition. Charge by weight where the nameplate gives it; the superheat method suits fixed-orifice systems, the subcooling method suits TXV systems.
Worked example
A split unit is nameplated R-410A, 1.2 kg. R-410A has a GWP of 2088, so the charge equals 1.2 × 2088 = 2506 kg CO2e, about 2.5 tonnes. Under the Kigali Amendment this is the number that matters - R-410A has zero ODP, so ozone depletion is not the issue here.
Traps
Topping up a blend as a vapour; using mineral oil with an HFC; treating R-22 and R-410A as interchangeable (R-410A runs roughly 60 % higher pressure); and quoting GWP when the question asks for ODP.