NEET Physics Mock Test

Units, Measurements & Dimensions

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NEET Physics Mock Test

Units, Measurements & Dimensions

NEET Physics Mock Test

Units, Measurements & Dimensions

Time: 25 minutes

Questions: 10

Marks: 40

NTA Pattern: +4 / -1

Instructions

• This test follows the official NEET exam pattern and marking scheme
• Each question carries 4 marks for correct answer
• 1 mark will be deducted for each incorrect answer
• Select your answer by clicking on the option
• Click "Show Answer" to verify your response and see explanation
• Ensure you complete the test within the given time limit

Time Remaining: 25:00

1

The dimensional formula for thermal conductivity is:

[A] \( \text{M}^1\text{L}^1\text{T}^{-3}\Theta^{-1} \)

[B] \( \text{M}^1\text{L}^{-3}\text{T}^{-1}\Theta^{-1} \)

[C] \( \text{M}^1\text{L}^1\text{T}^{-3}\Theta \)

[D] \( \text{M}^3\text{L}^{-1}\text{T}^{-3}\Theta \)

Answer: [A]

Explanation: Thermal conductivity (k) relates to heat flux per unit temperature gradient. Derived from Fourier's law: \([k] = \frac{[\text{Energy}]}{[\text{Time}][\text{Length}][\text{Temperature}]} = \text{M}^1\text{L}^1\text{T}^{-3}\Theta^{-1}\).

2

Newton-second is the unit of:

[A] Velocity

[B] Angular momentum

[C] Momentum

[D] Energy

Answer: [C]

Explanation: Newton-second = \(\text{kg·m·s}^{-1}\), matching momentum (\(p = mv\)).

3

A light-year is a unit of:

[A] Time

[B] Distance

[C] Energy

[D] Luminous intensity

Answer: [B]

Explanation: Light-year measures the distance light travels in one year.

4

Which pair has identical dimensions?

[A] Stress and Pressure

[B] Tension and Surface tension

[C] Planck's constant and Angular momentum

[D] Angle and Strain

Answer: [C]

Explanation: Both Planck's constant (\(h\)) and angular momentum (\(L\)) have dimensions \( \text{M}^1\text{L}^2\text{T}^{-1} \).

5

The SI unit of luminous intensity is:

[A] Candela

[B] Lux

[C] Lumen

[D] Tesla

Answer: [A]

Explanation: Candela is the SI base unit for luminous intensity.

6

If \(L = 2.331 \text{cm}\) and \(B = 2.1 \text{cm}\), \(L + B =\)?

[A] 4.431 cm

[B] 4.43 cm

[C] 4.4 cm

[D] 4 cm

Answer: [C]

Explanation: \(2.331 + 2.1 = 4.431\), rounded to one decimal place (since 2.1 has least precision: ±0.1 cm) → 4.4 cm.

7

The mass of a silver wire is \((0.6 \pm 0.006) \text{g}\), radius \((0.5 \pm 0.005) \text{mm}\), length \((4 \pm 0.04) \text{cm}\). Maximum % error in density is:

[A] 4%

[B] 3%

[C] 6%

[D] 7%

Answer: [A]

Explanation: Density \(\rho = \frac{m}{\pi r^2 l}\). % error: \[ \left(\frac{\Delta \rho}{\rho}\right)_{\text{max}} = \frac{\Delta m}{m} + 2\frac{\Delta r}{r} + \frac{\Delta l}{l} = 1\% + 2\% + 1\% = 4\% \]

8

In vernier calipers, 20 vernier divisions match 16 main scale divisions (1 MSD = 1 mm). Least count = ?

[A] 0.02 mm

[B] 0.05 mm

[C] 0.1 mm

[D] 0.2 mm

Answer: [D]

Explanation: \[ \text{Least count} = 1 \text{ MSD} - 1 \text{ VSD} = 1 - \frac{16}{20} = 0.2 \text{ mm} \]

9

Which of the following pairs have the same dimensions?

[A] Energy and Angular momentum

[B] Impulse and Momentum

[C] Power and force

[D] Stress and Pressure

Answer: [B]

Explanation: Both have dimension \(MLT^{-1}\).

10

The SI unit of universal gravitational constant (G) is:

[A] N·m²/kg²

[B] J/kg·K

[C] m/s²

[D] kg/m³

Answer: [A]

Explanation: \(F = G\frac{m_1 m_2}{r^2}\) gives the unit.

NEET Preparation Tips

• Prioritize NCERT: 80% of NEET Physics is from NCERT. Master derivations, examples, and exercises.
• Formula Notebook: Maintain chapter-wise formulas for quick revision.
• Error Analysis: Practice % error and propagation problems—highly recurring topic.
• Mock Tests: Solve 1-2 timed tests weekly to build speed and accuracy.
• Dimensional Analysis: Master dimensional formulas and their applications.

Key Dimensional Formulas

Physical Quantity	Dimensional Formula
Thermal conductivity	\( \text{M}^1\text{L}^1\text{T}^{-3}\Theta^{-1} \)
Planck's constant	\( \text{M}^1\text{L}^2\text{T}^{-1} \)
Pressure	\( \text{M}^1\text{L}^{-1}\text{T}^{-2} \)
Surface tension	\( \text{M}^1\text{T}^{-2} \)
Gravitational constant	\( \text{M}^{-1}\text{L}^3\text{T}^{-2} \)
Viscosity	\( \text{M}^1\text{L}^{-1}\text{T}^{-1} \)

Answer Key

Q No.	Answer
1	A
2	C
3	B
4	C
5	A
6	C
7	A
8	D
9	B
10	A

NEET Physics Mock Test | Units, Measurements & Dimensions | © 2023 PhysicsMaster Pro