Which refrigerant is most commonly used as a replacement for R-12 in new household refrigerators?

B. R-134a is indeed the commonly used refrigerant as a replacement for R-12 in new household refrigerators. The transition away from R-12, which is a chlorofluorocarbon (CFC), was primarily due to environmental concerns related to ozone depletion. R-134a is a hydrofluorocarbon (HFC) that does not contribute to ozone depletion and has a much lower global warming potential compared to many alternatives.

R-134a gained popularity because it operates efficiently in household refrigeration systems and is more environmentally friendly than CFCs. Many manufacturers specifically designed their systems to accommodate R-134a, ensuring compatibility and optimal performance in modern refrigeration units.

In contrast, R-22 is often used in air conditioning systems rather than refrigeration; R-404A is typically utilized in commercial applications and not in standard household refrigerators; while R-410A is prevalent in new air conditioning systems and not a direct replacement for household refrigerator applications. Thus, R-134a stands out as the right choice for replacing R-12 in household refrigerators.