Pressure equivalence (reframed for uniqueness):\r Which of the following values is <em>not</em> approximately equal to 1 kgf/cm^2 (standard gravity, water at 4°C)?

Introduction:
Engineering practice frequently interconverts legacy pressure units such as kgf/cm^2, bar, kPa, mmHg (torr), and water column. Recognizing near-equivalences helps in quick estimates and in reading older datasheets while avoiding significant errors.

Given Data / Assumptions:

• Standard gravity g = 9.80665 m/s^2.
• 1 kgf = force exerted by 1 kg mass under standard gravity.
• Water density ρ ≈ 1000 kg/m^3 at 4°C for head equivalence.

Concept / Approach:
By definition, 1 kgf/cm^2 = 98,066.5 Pa = 98.07 kPa ≈ 0.967 bar. Hydrostatic equivalence gives about 10 m of water column. Converting to mmHg: 98,066.5 Pa ÷ 133.322 Pa/mmHg ≈ 735.6 mmHg. Therefore, values like 0.967 bar, 98.07 kPa, 10 m wc, and 735.6 mmHg are consistent with 1 kgf/cm^2, whereas exactly 1.000 bar (100 kPa) is slightly higher (~2% difference) and thus not equal.

Step-by-Step Solution:
Start from SI: 1 kgf/cm^2 = 98,066.5 Pa.Convert to bar: 98,066.5 Pa / 100,000 Pa/bar ≈ 0.967 bar.To kPa: 98.07 kPa (direct).To water head: P = ρ g h ⇒ h ≈ 10 m.To mmHg: 98,066.5 / 133.322 ≈ 735.6 mmHg.

Verification / Alternative check:
Cross-checks using multiple routes (e.g., bar and head) converge consistently, confirming the small mismatch with 1.000 bar.

Why Other Options Are Wrong:

• 0.967 bar, 98.07 kPa, 10 m wc, 735.6 mmHg: All are established approximations for 1 kgf/cm^2.

Common Pitfalls:
Assuming 1 kgf/cm^2 equals exactly 1 bar or 100 kPa; the difference (~2%) can matter in precise calculations.

Final Answer:
1.000 bar