Which of the following pairs is NOT correctly matched Quantity S. I. Unit (a) Activity of radio-active substance Curie (b) Power of lense Diopter (c) Heat Joule (d) Pressure Pascal?

Option 1 : (a)

The correct answer is (a).

Activity of radio-active substance:

• The SI unit of radioactivity is becquerel (Bq) and this term is named after Henri Becquerel. Hence, pair (a) is not correct.
• Unit of radioactivity is defined as the activity of a quantity of radioactive material where one decay takes place per second.

​Power of lense:

• The power of a lens is equal to the reciprocal of the focal length of the lens.
• SI unit of power is Dioptre (D). Hence, pair (b) is correct.

​Heat:

• The unit of quantity of heat is the joule (J). Hence, pair (c) is correct.
• Heat flow may be expressed as joules per second (J/s)
• A joule is a derived unit of energy in the International System of Units.
• It is equal to the amount of work done when a force of 1 newton displaces a mass through a distance of 1 metre in the direction of the force applied.

​Pressure:

• The pascal is the SI-derived unit of pressure used to quantify internal pressure, stress, Young's modulus, and ultimate tensile strength. Hence, pair (d) is correct.
• A pascal is a pressure of one newton per square metre.