Standard conditions in gas calculations: STP (standard temperature and pressure) corresponds to which of the following sets of conditions?

Introduction / Context:
Standard states are reference conditions used to report and compare thermophysical data. In gas laws and stoichiometry, STP is a conventional benchmark that allows consistent molar volume and property comparisons across textbooks and problems.

Given Data / Assumptions:

• Classical chemistry/physics convention for STP.
• 1 atm = 760 torr = 101.325 kPa.
• Temperature scales: 0°C = 273.15 K; 15.5°C = 288.65 K.

Concept / Approach:
Traditional STP used in many educational contexts is 1 atm pressure and 0°C temperature. Pressure is commonly expressed as 760 torr (or 760 mm Hg absolute), not gauge pressure. Recognize the distinction between absolute and gauge pressures: gauge excludes atmospheric baseline, absolute includes it.

Step-by-Step Solution:
Identify temperature: STP → 0°C (273.15 K).Identify pressure: STP → 1 atm absolute = 760 torr.Match the option that states both: '760 torr and 0°C'.

Verification / Alternative check:
Using the ideal gas law at STP gives classic molar volume values (about 22.414 L/mol under the older STP convention), reinforcing that STP is 1 atm and 0°C in many curricula.

Why Other Options Are Wrong:
Options with gauge pressure are incorrect reference states; 15.5°C corresponds to NTP-like conditions, not STP.

Common Pitfalls:

• Confusing STP (0°C) with NTP or SATP (near 20–25°C).
• Using gauge instead of absolute pressure in gas calculations.

Final Answer:
760 torr and 0°C