Units and Measurements — Class 11 MCQs with Answers
Class 11 CBSE Physics · Chapter 2
68 practice questions · 23 Easy · 23 Medium · 22 Hard · Updated
Practise the most important Class 11 CBSE Physics questions from Chapter 2, "Units and Measurements". You get 6 timed quizzes made from 68 NCERT-based MCQs, with answers and explanations. The questions are split into 23 Easy, 23 Medium and 22 Hard. Warm up on the basics, then move on to the exam-level questions that set top scorers in CBSE & Maharashtra HSC Board exams, JEE Main, MHT-CET, JEE Advanced and NEET UG apart.
To score well in "Units and Measurements", focus on numericals, derivations and applying concepts. Each MCQ here is timed and uses exam-style marking (+4 correct, −1 wrong, 0 skipped). This trains you to stay accurate under time pressure, as real papers need. Every question has a short explanation, so a wrong answer becomes a quick lesson. It is the fastest way to fix gaps before a test.
Use this chapter for focused revision. Start with the Easy set to check your basics on Units and Measurements, then move to Medium and Hard to practise applying them. Your accuracy, streaks and XP save automatically. This chapter also adds to your overall Class 11 Physics mastery score. 13 sample questions are solved in full below, with the answer and a worked explanation. Sign in free to start practising.
Key concepts: Units and Measurements (Class 11 Physics)
Every physical measurement carries a unit and an uncertainty, and this chapter builds the machinery for both: the seven SI base units, dimensional formulae and the homogeneity check, significant figures, and the rules for how errors combine when measured quantities are added, multiplied or raised to powers.
- SI base units
- Seven independent units — metre, kilogram, second, ampere, kelvin, mole and candela. Every other unit in physics is derived from these by multiplication or division.
- Derived units
- Units built from the base set, such as the newton (kg m s⁻²) and the pascal (N m⁻²). Recognising a derived unit's build is often faster than recalling its formula.
- SI prefixes
- Standard multipliers attached to any unit — kilo for 10³, milli for 10⁻³, micro for 10⁻⁶, nano for 10⁻⁹ and giga for 10⁹ — which keep numbers readable across huge ranges.
- Dimensional formula
- A quantity written as powers of the base dimensions M, L, T (and A, K, mol, cd). Pressure is [M L⁻¹ T⁻²]; energy and work share [M L² T⁻²].
Units and Measurements — important questions & MCQs with answers (Class 11 Physics)
13 solved questions from this chapter's difficulty levels, each with its answer and explanation. The other 55 are timed and scored when you sign in.
- Q1Easy
The SI unit of force is:
A.Newton✓ CorrectB.DyneC.JouleD.PascalAnswer: A. Newton
Explanation: Newton's second law fixes force = mass × acceleration, so its SI unit is the newton (1 N = 1 kg·m·s⁻²). Dyne is the CGS unit — a common mix-up to avoid.
- Q2Easy
How many significant figures are there in 0.00450?
A.2B.3✓ CorrectC.4D.5Answer: B. 3
Explanation: In 0.00450, the leading zeros before 4 only fix the decimal point and are not significant; 4, 5, and the trailing 0 count, giving 3 significant figures, not 5.
- Q3Easy
Dimensions of force:
A.[M L T]B.[M L T⁻²]✓ CorrectC.[L T⁻²]D.[M T⁻²]Answer: B. [M L T⁻²]
Explanation: Newton's second law gives F = ma, so dimensions are [M][L T⁻²] = [M L T⁻²]. Dropping the T⁻² and writing [M L T] is the usual careless slip.
- Q4Easy
Significant figures in 0.00230:
A.3✓ CorrectB.5C.4D.2Answer: A. 3
Explanation: In 0.00230, the leading zeros are placeholders, not significant; 2, 3, and the trailing 0 after the decimal are significant, giving 3 sig figs, not 5.
- Q5Easy
Prefix 'kilo' means:
A.10³✓ CorrectB.10⁶C.10⁻³D.100Answer: A. 10³
Explanation: The SI prefix 'kilo' means 10³ (a factor of one thousand), as in 1 kilogram = 10³ grams. Confusing it with 'mega' (10⁶) or 'milli' (10⁻³) is the common slip.
- Q6Medium
SI unit of electric charge:
A.VoltB.Coulomb (= A·s)✓ CorrectC.WattD.OhmAnswer: B. Coulomb (= A·s)
Explanation: Charge Q = I·t, so its SI unit is the coulomb, built from ampere times second: 1 C = 1 A·s. Confusing it with the volt (potential) is the usual slip.
- Q7Medium
Two quantities are A = 5.0 ± 0.1 and B = 2.0 ± 0.1. The maximum percentage error in A × B is approximately:
A.2%B.7%✓ CorrectC.5%D.12%Answer: B. 7%
Explanation: For a product, percentage errors add: (0.1/5.0)×100 + (0.1/2.0)×100 = 2% + 5% = 7%. Picking just one term's error (2% or 5% alone) is the common shortcut mistake.
- Q8Medium
Dimensions of Planck's constant h:
A.[M L² T⁻¹]✓ CorrectB.[M L T⁻²]C.[M L² T⁻²]D.[M L T⁻¹]Answer: A. [M L² T⁻¹]
Explanation: From E = hν, h = E/ν, so its dimensions are [M L² T⁻²]/[T⁻¹] = [M L² T⁻¹]. Forgetting to invert frequency's T⁻¹ gives the wrong [M L² T⁻²].
- Q9Medium
Result of (5.00 + 0.0023) has how many decimal places?
A.1B.4C.3D.2 (limited by 5.00)✓ CorrectAnswer: D. 2 (limited by 5.00)
Explanation: When adding, the sum is rounded to the fewest decimal places among the terms; 5.00 has only 2 decimal places, so 5.00 + 0.0023 must be reported to 2 decimals.
- Q10Medium
The dimensional formula of pressure is:
A.[M L⁻¹ T⁻²]✓ CorrectB.[M L T⁻²]C.[M L² T⁻²]D.[M L⁻² T⁻²]Answer: A. [M L⁻¹ T⁻²]
Explanation: Pressure = Force/Area, so [M L T⁻²]/[L²] gives [M L⁻¹ T⁻²]. Mixing up numerator and denominator powers of L is what makes [M L T⁻²] a tempting wrong pick.
- Q11Hard
If the percentage error in measuring the radius of a sphere is 2%, the percentage error in its volume is:
A.2%B.4%C.8%D.6%✓ CorrectAnswer: D. 6%
Explanation: V = (4/3)πr³, so a relative-error rule gives ΔV/V = 3×(Δr/r) = 3×2% = 6%. Forgetting the power-of-3 multiplier and just doubling to 4% is the usual slip.
- Q12Hard
If C is capacitance and V is potential, dimensions of CV² are:
A.VoltageB.ChargeC.PowerD.Energy [M L² T⁻²]✓ CorrectAnswer: D. Energy [M L² T⁻²]
Explanation: Energy stored in a capacitor is ½CV², and since ½ is dimensionless, CV² itself carries the dimensions of energy, [M L² T⁻²], not just voltage or charge.
- Q13Hard
Result of (1.23 + 2.345 + 0.001):
A.3.58 (limited to 2 decimal places)✓ CorrectB.3.576C.3.6D.3.5Answer: A. 3.58 (limited to 2 decimal places)
Explanation: Adding gives 1.23 + 2.345 + 0.001 = 3.576, but the result is limited to the least precise term's 2 decimal places (from 1.23), so it rounds to 3.58.
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Start this chapter free →Units and Measurements — FAQs
What are the key concepts in Class 11 Physics Units and Measurements?+
Every physical measurement carries a unit and an uncertainty, and this chapter builds the machinery for both: the seven SI base units, dimensional formulae and the homogeneity check, significant figures, and the rules for how errors combine when measured quantities are added, multiplied or raised to powers. Key ideas include SI base units, Derived units, SI prefixes, Dimensional formula.
What does Class 11 Physics Chapter 2 (Units and Measurements) cover on XamBaaz?+
It has 68 NCERT-based MCQs on "Units and Measurements": 23 Easy, 23 Medium and 22 Hard. Together they make 6 timed quizzes, and you never get the same set twice. Every question has an instant explanation. They help you prepare for CBSE & Maharashtra HSC Board exams, JEE Main, MHT-CET, JEE Advanced and NEET UG.
Are these "Units and Measurements" questions free to practise?+
Yes. Sign in with Google to practise "Units and Measurements" free. Full unlimited access is ₹999/year on a launch offer until 1 December 2026. No chapter is charged separately.
How should I revise "Units and Measurements" for the exam?+
Start with the Easy quiz to check your basics, then try Medium and Hard to practise applying them. There are 6 timed quizzes on this chapter, so you can come back for a fresh set instead of one you have seen. Read each explanation, retry the questions you miss, and track your accuracy until it stays high.
Are these "Units and Measurements" MCQs available with answers?+
Yes. 13 sample questions are shown here in full, each with the correct option and a step-by-step "Why" explanation. Sign in free with Google to start practising, with instant scoring.
Is there negative marking in the "Units and Measurements" quizzes?+
Yes. The timed quizzes use exam-style marking: +4 for a right answer, −1 for a wrong one and 0 for a skip, the same negative marking as JEE Main, JEE Advanced and NEET UG. MHT-CET and CBSE board papers have no negative marking. Our mocks for those are scored their way.
What are the important questions from Units and Measurements (Class 11 Physics)?+
The questions that matter most test SI base units, Derived units, SI prefixes, Dimensional formula. This page shows 13 solved important MCQs with answers and explanations; all 68 questions on the chapter are available as timed quizzes once you sign in.
Is there an online quiz for Units and Measurements?+
Yes — Class 11 Physics Units and Measurements has timed online quizzes at Easy, Medium and Hard levels, with instant scoring and a worked explanation on every question. The first quiz on the chapter is free.