In radiography, fixing removes unexposed silver halide from the film emulsion to lock in the image. The chemical that does this best is sodium thiosulfate, which dissolves the unexposed silver halide as a soluble thiosulfate complex, leaving the developed image intact and stable when washed and dried. Sodium sulfite is typically included in fixers as a preservative to prevent thiosulfate oxidation and reduce fog, but it is not the primary fixing agent. Sodium bicarbonate is mainly a buffering or pH-adjusting agent in other solutions, not a fixer, and hydrochloric acid would damage the emulsion rather than fix it.

Waste segregation and disposal for anatomical material is the main concept here. Biopsies and body parts are considered anatomical waste and must be handled as regulated medical waste, going into red anatomical waste containers so they’re treated separately from general waste and disposed of by controlled methods, typically incineration. Blue general waste is for nonhazardous everyday waste, yellow bag with stripe is used for infectious or cytotoxic waste in many settings, and green recyclable waste is for recyclables. Therefore, red anatomical waste is the correct choice.

Leucocytosis is the term for a high white blood cell count. White blood cells rise in response to infection, inflammation, tissue damage, or stress, as the body ramps up its defense. Normal ranges vary by lab, but a higher-than-normal WBC count is labeled leucocytosis and can be seen with infections or hematologic conditions like leukemia, among other causes. Leucopenia means a low white blood cell count, anemia refers to low red blood cells or hemoglobin, and thrombocytopenia refers to a low platelet count. So, the term that describes a high white blood cell count is leucocytosis.

This question centers on redox changes and how shifting oxidation state can change both the appearance and form of a solid. Turning exposed crystals into grains of black is describing a reduction process—gaining electrons or removing oxygen from a compound to reach a more reduced state. When oxide materials are reduced, they often become metallic and break down into fine, dark grains; the fine dispersion of metal can look black because of how light interacts with many tiny particles. Oxidation, by contrast, would add oxygen to the material, forming oxides that are often colored differently (red, brown, or other hues) rather than producing black grains. Precipitation is about forming a solid from solution without necessarily altering oxidation state, and ionization involves removing electrons to create ions rather than forming solid black grains.