Question

Which of the following is not a basic physical quantity?
A.) Length
B.) Time
C.) Density
D.) Amount of substance

Answer 1

Hint: Quantities to which we can measure or quantify them or we can say that we can measure their physical presence and we can’t derive these basic quantities from other quantities. They have fundamental units also.

Step by step solution:
A physical quantity is a property of a material or system that can be quantified by measurement. A physical quantity can be expressed as the combination of a numerical value and a unit. For example physical quantity mass can be quantified as ‘n kg’, where n is numerical value and kg is the unit.
Basically physical quantities are of two types one is base quantities or fundamental quantities and other is derived quantities. We know that there are seven fundamental physical quantities: time, length, mass, Amount of substance, luminous intensity, temperature, and electric current.
And there are other physical quantities which are derived from these basic physical quantities.
Corresponding to these basic physical quantities some basic physical units are also there. Those are in SI units: mass(kilogram(kg)), length(meter(m)), time(second(s)), temperature(Kelvin(K)), amount of substance(mole(mol)), electric current (ampere(A)), and luminous intensity (candela(cd)).
Here in this question length, time and amount of substance are basic physical quantities; they are not derived from any other quantity, whereas density is a derived physical quantity from mass and volume (length).
So, from the above explanation it is clear that density is not a basic physical quantity.
Then the correct answer is “C”.

Note: Here you should remember these basic physical quantities and other than these basic quantities all others are derived from basic physical quantities.