Which to the following is NOT a fundamental unit?

Step 1: Analyze the question You are asked to find the unit that is NOT a fundamental (base) SI unit. That means four of the options are base units and one is a derived unit.

Step 2: The concept The SI system has seven fundamental units:

| Quantity | Unit | |---|---| | Length | metre (m) | | Mass | kilogramme (kg) | | Time | second (s) | | Electric current | ampere (A) | | Temperature | kelvin (K) | | Amount of substance | mole (mol) | | Luminous intensity | candela (cd) |

Derived units are formed by combining fundamental units, for example through multiplication or division.

Step 3: Check each option

• A. Ampere: fundamental unit of electric current.
• B. Kelvin: fundamental unit of temperature.
• C. Kilogramme: fundamental unit of mass.
• D. Newton: the unit of force. From F = ma, 1 N = 1 kg·m/s² (kg m s⁻²). It is built from kg, m and s, so it is derived.
• E. Second: fundamental unit of time.

Step 4: Answer The Newton is the only derived unit in the list, so the correct option is D.

Exam tip: Remember that the fundamental units are "My Kind Sister Always Keeps Mango Candy" (Metre, Kilogramme, Second, Ampere, Kelvin, Mole, Candela). Any unit named after a scientist that measures a combined quantity, such as Newton, Joule, Watt, Pascal or Coulomb, is usually derived. The exceptions are the ampere and kelvin, which are fundamental. Always check whether the unit can be written using kg, m, s, A, K, mol or cd.