Which of the following is not an SI unit?

The correct answer is option 2) i.e. atomic mass unit

CONCEPT:

• Mass is the measure of the amount of matter present in an object.
  • It is the basic property of matter around us.
  • The SI unit of mass is the kilogram (kg).
• While dealing with atoms and molecules, the kilogram is an inconvenient unit. In this case, there is an important standard unit of mass, called the unified atomic mass unit (u).
  • ​1 unified atomic mass unit = 1u = 1/12 of the mass of an atom of the carbon-12 isotope

EXPLANATION:

• The kilogram is the SI unit of mass.
• Newton is the SI unit of force.
• mole is the SI unit of the amount of substance of a specified elementary entity.
• The atomic mass unit is a standard unit of mass and not an SI unit.