Identifying the Incorrect Physical Quantity and Unit Pair

This question requires identifying the incorrect match between a physical quantity and its standard unit of measurement. Let's analyze each option:

Option Analysis

• 1. Power - Watt: Power is defined as the rate at which work is done or energy is transferred. Its SI unit is the Watt (W). This pair is correct.
• 2. Pressure - Newton: Pressure is defined as force applied perpendicular to the surface of an object per unit area ($P = \frac{F}{A}$). The SI unit of force is the Newton (N), and the SI unit of area is square meters ($m^2$). Therefore, the SI unit of pressure is Pascal (Pa), where $1 \text{ Pa} = 1 \text{ N/m}^2$. Newton (N) is the unit of force, not pressure. This pair is incorrect.
• 3. Frequency - Hertz: Frequency measures how often a periodic event occurs. Its SI unit is the Hertz (Hz), where $1 \text{ Hz} = 1 \text{ cycle per second}$. This pair is correct.
• 4. Energy - Joule: Energy is the capacity to do work. Its SI unit is the Joule (J). This pair is correct.

Conclusion

The pair that incorrectly matches a physical quantity with its unit is Pressure - Newton. The correct unit for pressure is Pascal (Pa).