JEE Advanced paper is considered to be one of the toughest entrance exams in India. Moreover, this Physics is considered the toughest subject because it is the most application-based. The student needs to get the basics right and then move on to mastering advanced concepts. Units and Measurements consist of nearly about 3-4 % of marks in the Physics section.

**Q1. Statement 1: The dimensions of rate of flow are [M**

Statement 2: Rate of flow is velocity/sec.

^{0}L^{3}T^{-1}]Statement 2: Rate of flow is velocity/sec.

**Q2. Statement 1: Avogadro number is not a dimensionless constant.**

**Statement 2: It is number of atoms is one gram mole.**

Solution

(a)

Avogadro number has the unit per gram mole. So, it is not dimensionless.

(a)

Avogadro number has the unit per gram mole. So, it is not dimensionless.

**Q3. Statement 1: Dimensional constants are the quantities whose values are constant**

Statement 2: Dimensional constants are dimensionless

Statement 2: Dimensional constants are dimensionless

Solution

(c)

Dimensional constants are the quantities whose values are constant, and they possess dimensions. For example, the velocity of light in vacuum, universal gravitational constant, Boltzmann constant, Planck’s constant, etc.

(c)

Dimensional constants are the quantities whose values are constant, and they possess dimensions. For example, the velocity of light in vacuum, universal gravitational constant, Boltzmann constant, Planck’s constant, etc.

**Q4. Statement 1: Linear mass density has the dimensions of [M**

_{1}L_{-1}T_{0}]**Statement 2: Because density is always mass per unit per volume**

Solution

(c)

Density is not always mass per unit volume

(c)

Density is not always mass per unit volume

**Q5. Statement 1: The unit used for measuring nuclear cross-section is barn.**

Statement 2: 1 barn = 10

Statement 2: 1 barn = 10

^{-4}m^{2}.
Solution

(c)

Nuclear cross-section is measured in unit barn. but in SI system the value of 1 barn=10

(c)

Nuclear cross-section is measured in unit barn. but in SI system the value of 1 barn=10

^{-28}m^{2}. Therefore, assertion is true, and reason is false.**Q6. Statement 1: The unit used for measuring nuclear cross-section is barn.**

Statement 2: 1 barn = 10

Statement 2: 1 barn = 10

^{-4}m^{2}.
Solution

(c)

Nuclear cross-section is measured in unit barn. but in SI system the value of 1 barn=10

(c)

Nuclear cross-section is measured in unit barn. but in SI system the value of 1 barn=10

^{-28}m^{2}. Therefore, assertion is true, and reason is false.**Q8. Statement 1: Linear momentum and impulse have same dimensions [M L T**

Statement 2: Impulse is equal to final momentum

^{-1}]Statement 2: Impulse is equal to final momentum

Solution

(c)

Impulse is equal to change in momentum. Dimensionally both are the same

(c)

Impulse is equal to change in momentum. Dimensionally both are the same

**Q9. Statement 1: â„« (Angstrom) and AU are different units of length**

**Statement 2: â„« (Angstrom) is a small unit of length while AU is a big unit of length**

Solution

(a)

â„« is equal to 10

(a)

â„« is equal to 10

^{-10}m, whereas 1 AU is the distance between Sun and Earth