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NEET Units and Measurements: 5 practice MCQs with answers

By the PrepMatic team · Updated 9 Oct 2026 · 4 min read

Units and Measurements is the first chapter of NEET Physics, and it feeds every numerical you will meet later. The five MCQs below test dimensional formulae, significant figures, error propagation and the least count of a Vernier caliper, all at NCERT Class 11 level, and each answer is explained step by step.

What this chapter covers in the NEET syllabus

The NMC syllabus lists the first Physics unit as Physics and Measurement. In NCERT it is the Class 11 chapter Units and Measurements. The topics that produce questions are:

• SI base units and derived units, and the dimensional formula of common quantities.
• Dimensional analysis: checking a formula, converting units and deriving a relation, along with its limits.
• Significant figures and rounding rules for sums and products.
• Absolute, relative and percentage error, and how errors combine.
• Least count of a Vernier caliper and a screw gauge, and zero error. The separate Experimental Skills unit builds on this.

Five practice MCQs on Units and Measurements

Question 1

The dimensional formula of Planck's constant h is:

• A. [ML²T⁻²]
• B. [MLT⁻¹]
• C. [ML²T⁻¹]
• D. [ML⁻¹T⁻¹]

Question 2

The number of significant figures in the measurement 0.04050 m is:

• A. 4
• B. 3
• C. 5
• D. 2

Question 3

The side of a cube is measured with a percentage error of 2%. The percentage error in its volume is:

• A. 3%
• B. 6%
• C. 8%
• D. 9%

Question 4

In a Vernier caliper, 10 Vernier scale divisions coincide with 9 main scale divisions, and one main scale division is 1 mm. The least count of the instrument is:

• A. 0.9 mm
• B. 0.1 cm
• C. 0.01 cm
• D. 0.001 cm

Question 5

Which of the following pairs of physical quantities has the same dimensions?

• A. Force and pressure
• B. Work and power
• C. Energy and power
• D. Impulse and momentum

Answers and explanations

1. C. Planck's constant comes from E = hν, so h = E/ν. Energy has dimensions [ML²T⁻²] and frequency has [T⁻¹], giving [ML²T⁻¹], the same as angular momentum. Option A is the dimension of energy itself.
2. A. In 0.04050 the leading zeros only fix the position of the decimal point, so they do not count. The digits 4, 0, 5 and the final 0 after the decimal point are significant, which makes four.
3. B. Volume is V = a³, so the relative error in V is three times the relative error in a. That is 3 × 2% = 6%.
4. C. Least count = 1 MSD − 1 VSD. Here 1 MSD = 1 mm and 1 VSD = 0.9 mm, so the least count is 0.1 mm = 0.01 cm. The 0.9 mm in option A is the length of one Vernier division, not the least count.
5. D. Impulse = force × time and momentum = mass × velocity, and both are [MLT⁻¹]. Force [MLT⁻²] and pressure [ML⁻¹T⁻²] differ, work [ML²T⁻²] and power [ML²T⁻³] differ, and energy and power differ by a factor of time.

How to prepare Units and Measurements

Treat this chapter as a toolkit, not a list of facts to memorise.

• Derive dimensional formulae, do not rote-learn them. Start from a defining equation such as F = ma, P = F/A or E = hν. Make a one-page table of about 25 quantities and test yourself for a week.
• Use dimensions as a check. Both sides of a correct equation have the same dimensions, and only quantities with the same dimensions can be added. The method cannot find pure numbers such as ½ or 2π, and it cannot handle trigonometric or exponential functions of dimensional arguments.
• Remember how errors combine. In a sum or difference the absolute errors add. In a product or quotient the relative errors add, and a power multiplies the relative error by that power. Errors never subtract, which is the most common slip.
• Practise reading instruments. Work through a few Vernier and screw gauge readings with zero error, since the same idea appears in the Experimental Skills unit.

This chapter is short, so one focused day plus daily revision of the formula table is enough to make it reliable. For the order in which to study the rest of Physics, see the NEET Physics preparation guide, and for the full unit list see the NEET syllabus.

Take a full Units and Measurements test on PrepMatic

This short chapter is a good first test to take. A PrepMatic topic test runs about 15 questions in 30 minutes and is scored with NEET's negative marking, so you also see what careless slips on significant figures and units cost you. The free Basic plan includes topic tests, and the practice hub lists the next chapters.

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