Concept:The boiling point of a liquid is the temperature at which its vapor pressure equals the external atmospheric pressure. Increasing external pressure raises the boiling point.
Formula:$$ \text{Vapor Pressure} = \text{External Pressure} $$
Solution:- Standard atmospheric pressure is \( 760 \text{ mmHg} \), at which water boils at \( 100^\circ\text{C} \).
- When the pressure is increased to \( 1489 \text{ mmHg} \) (approximately 2 atmospheres, matching conditions inside a standard pressure cooker), the vapor pressure must also reach \( 1489 \text{ mmHg} \) for boiling to occur.
- Water reaches this vapor pressure at approximately \( 120^\circ\text{C} \).
Why other options are incorrect:Options B, C, and D are lower temperatures which correspond to lower external vapor pressures. \( 100^\circ\text{C} \) strictly applies only to standard pressure (\( 760 \text{ mmHg} \)).
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