Which of the following is a base SI unit?

Solution

Physics sir · 2 steps

Ask of each unit: can it be broken into other SI units? Only the candela cannot.

1. Seven base units. SI has exactly seven base units: metre, kilogram, second, ampere, kelvin, mole and candela. Every other SI unit is built from these, so it is a derived unit.

   Unit	Quantity	In base units	Type
   Newton	force	kg m s⁻²	derived
   Watt	power	kg m² s⁻³	derived
   Candela	luminous intensity	cannot be broken down	base
   Joule	energy	kg m² s⁻²	derived

2. So. The candela, the unit of luminous intensity, is the only base SI unit here. The answer is (c).

The idea to keep. Learn the seven base units by heart: m, kg, s, A, K, mol, cd. If a unit can be written using other units, it is derived, even if it is named after a scientist.

Answer from the NTA final answer key. Solution by PrepWiser.