Reference conditions in thermodynamics and gas laws The conditions of temperature and pressure equal to 0 °C (273 K) and 760 mm Hg are termed as ______ temperature and pressure.

Introduction / Context:
Engineers and chemists often refer to specific “reference” conditions of temperature and pressure so that gas volumes, densities, and other properties can be compared consistently. In many classical textbooks and exam syllabi, the pair 0 °C (273 K) and 760 mm Hg (1 atm) is given a specific name that you are expected to recall correctly.

Given Data / Assumptions:

• Temperature = 0 °C, i.e., 273 K.
• Pressure = 760 mm of mercury (approximately 1 atm = 101.325 kPa).
• Context is foundational thermodynamics and basic gas laws used in engineering education.

Concept / Approach:
Historically, two labels are used in practice: “NTP” (Normal Temperature and Pressure) and “STP” (Standard Temperature and Pressure). In many engineering and chemistry curricula, NTP corresponds to 0 °C and 1 atm. STP is sometimes defined the same way in older conventions, though modern standards may adopt slightly different pressure values. For this classical MCQ, 0 °C and 760 mm Hg aligns with the term “normal” temperature and pressure.

Step-by-Step Solution:
Identify temperature: 0 °C = 273 K.Identify pressure: 760 mm Hg ≈ 1 atm.Match with commonly taught term in basic gas-law problems: NTP = Normal Temperature and Pressure.Therefore fill the blank with “normal.”

Verification / Alternative check:
Typical gas-law examples compute molar volume at NTP using 22.4 L per g-mole at 0 °C and 1 atm, reinforcing the use of the “normal” label for these specific conditions in standard problems.

Why Other Options Are Wrong:

• Standard: may also be used in some references, but within this conventional framing the expected term is “normal.”
• Reference laboratory / base-line: informal, not the canonical label.
• Saturated: relates to phase equilibrium (e.g., saturated steam), not ambient reference conditions.

Common Pitfalls:
Assuming “standard” must always be correct; exam conventions frequently reserve “normal” for 0 °C and 1 atm. Always read the exact pair of numbers and align with the commonly taught terminology for your syllabus.

Final Answer:
normal