## MCQ Questions for Class 11 Physics: Ch 2 Units and Measurements 1. Out of the following pairs, which one does not have identical dimensions ?
(a) Angular momentum and Planck's constant
(b) Impulse and momentum
(c) Moment of inertia and moment of a force
(d) Work and torque
► (c) Moment of inertia and moment of a force

2. Which of the following physical quantities has different dimensions?
(a) Energy
(b) Watt hour
(c) Momentum
(d) Work
► (c) Momentum

3. Identify the pair whose dimensions are equal.
(a) Torque and work
(b) Stress and energy
(c) Force and stress
(d) Force and work
► (a) Torque and work

4. Dimensions cannot be used to
(a) check dimensional correctness of a formula
(b) convert units
(c) find value of the constant of proportionality in an equation
(d) deduce a relation among physical quantities
► (c) find value of the constant of proportionality in an equation

5. Two physical quantities whose dimensions are not same, cannot be :
(a) multiplied with each other
(b) divided
(c) added or substracted in the same expression
► (c) added or substracted in the same expression

6. A student measures the distance covered and time taken by a body under free fall which was intially at rest. He uses this data for estimating g, the acceleration due to gravity. If the maximum percentage error in measurement  of the distance and the time are e1 and e2 respectively, then the maximum possible percentage error in the estimation of g is
(a) e2 - e2
(b) e2 + 2e2
(c) e2 + e2
(d) e2 - 2e2
► (b) e2 + 2e2

7. The number of significant figures in the distance of one light year , 9.4605 × 1015 m is
(a) thirty
(b) five
(c) four
(d) three
► (b) five

8. The most suitable instrument for measuring the size of an atom is.
(a) Electron microscope
(b) Vernier calliper
(c) Optical Microscope
(d) Screw gauge
► (a) Electron microscope

9. In case of measurement of ‘g’, if error in measurement of length of pendulum is 2%, the percentage error in time period is1 %. The maximum error in measurement of g is
(a) 1 %
(b) 2 %
(c) 4 %
(d) No error
► (c) 4 %

10. The respective number of significant figures for the numbers 23.023, 0.0003 and 2.1 × 10–3 are
(a) 5, 1, 2
(b) 4, 4, 2
(c) 5, 1, 5
(d) 5, 5, 2
► (a) 5, 1, 2

11. Choose the correct statement(s)
(a) Topological sort can be used to obtain an evaluation order of a depending graph.
(b) Evaluation order for a dependency graph dicates the order in which the semantic rules are done
(c) Code generation is independent of the order in which the semantic actions are performed
(d) Both (a) and (b)
► (d) Both (a) and (b)

12. What is the number of significant figures in 0.310×103 ?
(a) 6
(b) 2
(c) 4
(d) 3
► (d) 3

13. Which of the following is not the unit of energy?
(a) watt-hour
(b) electron-volt
(c) N × m
(d) kg × m/sec2
► (d) kg × m/sec2

14. In an experiment the angles are required to be measured using an instrument. 29 divisions of the main scale exactly coincide with the 30 divisions of the vernier scale. If the smallest division of the main scale is half-a-degree (= 0.5°), then the least count of the instrument is
(a) One minute
(b) Half minute
(c) One degree
(d) Half degree
► (a) One minute

15. Electron volt is a unit of
(a) Potential difference
(b) Electric current
(c) Electronic charge
(d) Energy
► (d) Energy

16. Find the option with 3 significant figures.
(a) 0.0268
(b) 2.068
(c) 2.608
(d) 26.08
► (a) 0.0268

17. In the above question dimensions of b/c are the same as those of
(a) Wave velocity
(b) Wavelength
(c) Wave amplitude
(d) Wave frequency
► (a) Wave velocity

18. Which of the following is not the unit of time
(a) solar day
(b) parallactic second
(c) leap year
(d) lunar month
► (b) parallactic second

19. A dimensionless quantity
(a) has no unit
(b) must have a unit
(c) cannot exist
(d) May have a unit
► (d) May have a unit

20. Planck's constant has the dimensions of :
(a) force
(b) energy
(c) linear momentum
(d) angular momentum
► (d) angular momentum

21. Which pair of following quantities has dimensions different from each other
(a) Impulse and linear momentum
(b) Plank's constant and angular momentum
(c) Moment of inertia and moment of force
(d) Young's modulus and pressure
► (c) Moment of inertia and moment of force

22. After decimal point, number is less than 5 which is to be neglected,then retained number
(a) gets increased
(b) get decreased
(c) remains unchanged
(d) may decreased
► (c) remains unchanged

23. The product of energy and time is called action. The dimensional formula for action is same as that for
(a) Power
(b) Angular energy
(c) Force × velocity
(d) Impulse × distance
► (d) Impulse × distance

24. Which is the most accurate atomic clock?
(a) Carbon-12 clock
(b) Carbon atom clock
(c) Caesium atom clock
(d) Stop clock
► (c) Caesium atom clock
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