Thermodynamics reference point — absolute zero on Celsius scale: Choose the correct Celsius temperature that corresponds to absolute zero.

Introduction / Context:
Absolute zero is the theoretical temperature at which particles have minimum thermal motion. It anchors the Kelvin scale and has a fixed conversion to Celsius. Understanding this value is fundamental in physics, cryogenics, and semiconductor behavior at low temperatures.

Given Data / Assumptions:

• Absolute zero corresponds to 0 K on the Kelvin scale.
• Kelvin and Celsius scales have identical increments; they differ by an offset.
• Standard rounded conversion is requested.

Concept / Approach:
Use the conversion T_C = T_K − 273.15. Exact value is −273.15 °C; many basic multiple-choice contexts round to −273 °C. Recognize that 0 °C (freezing point of water) and 25 °C (room temperature) are far above absolute zero.

Step-by-Step Solution:
Start with absolute zero: T_K = 0.Convert to Celsius: T_C = 0 − 273.15 = −273.15 °C.Rounded choice closest to the exact value: −273 °C.

Verification / Alternative check:
Reverse conversion: −273.15 °C + 273.15 = 0 K. This confirms consistency between scales.

Why Other Options Are Wrong:
(a) 0 °C is the freezing point of water. (c) −276 °C is not the standard conversion. (d) 25 °C is ambient room temperature, not absolute zero.

Common Pitfalls:
Mixing −273 with −273.15; for scientific precision, keep two decimal places; for general MCQs, −273 °C is accepted.

Final Answer:
-273o C.