# MCQ Questions for Class 11 Physics Chapter 2 Units and Measurements with Answers

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## Units and Measurements Class 11 MCQs Questions with Answers

Multiple Type Choice Questions

Question 1.
Which of the following is not the name of physical quantity?
(a) Kilogram
(b) Density
(c) Impulse
(d) Energy

Question 2.
The weight of a body is 12g. This statement is not correct because
(a) The correct symbol for the unit of weight has not been used.
(b) The correct symbol for gram is gm.
(c) The weight should be expressed in kg.
(d) Of some reason other than those given above.

Answer: (a) The correct symbol for the unit of weight has not been used.

Question 3.
The density of a liquid is 13.6 g cm-3. Its value ip S.I. is
(a) 13.6 kgm-3
(b) 136 kgm-3
(c) 13600 kgm-3
(d) 1360 kgm-3

Answer: (a) 13.6 kgm-3

Question 4.
If the unit of force and length are doubled, the unit of energy will be
(a) 1/2 times
(b) 2 times
(c) 4 times
(d) 1/4 times

Answer: (c) 4 times

Question 5.
Which of the following have the same dimensions as $$\frac { v^2 }{ r }$$ Where v is the speed of the particle describing a circular path of radius r.
(a) Force
(b) Impulse
(c) Acceleration
(d) Momentum

Question 6.
Which of the following have the same dimensions as Plank’s constant?
(a) Moment of momentum
(b) Moment of fierce
(c) Momentum/distance
(d) Force/distance

Answer: (a) Moment of momentum

Question 7.
Which of the following is a dimensionless quantity, even when the measured quantity is not dimensionless?
(a) absolute error
(b) Gross error
(c) Relative error
(d) experimental error

Answer: (c) Relative error

Question 8.
The zero error belongs to the category of:
(a) constant error
(b) personal error
(c) accidental error
(d) instrumental error

Answer: (d) instrumental error

Question 9.
The least count of a stop watch is 0.1s. The time of 20 oscillations of the pendulum is found to be 20s. The percentage error in the time period is
(a) 0.25%
(b) 0.75%
(c) 0.50%
(d) 1.0%

Question 10.
The value of 0.98 – 0.989 with regard to the significant digit will be:
(a) 0.001
(b) 0.010 × 10-1
(c) 0.01 × 10-1
(d) None of these

Answer: (c) 0.01 × 10-1

Question 11.
What is the number of significant figures in (3.20 + 4.80) × 105?
(a) 2
(b) 3
(c) 4
(d) 5

Question 12.
Which of the following numerical values has three significant figures?
(a) 5.055
(b) 0.050
(c) 50.50
(d) 0.500

Question 13.
Which of the following is not the name of a physical quantity?
(a) Kilogram
(6) Density
(c) energy
(d) Impulse

Question 14.
A laser signal is sent towards the moon with a speed of light C and returns after a time f seconds. The distance of the moon from the observer is
(a) ct
(b) ct/2
(c) ct-2
(d) ct-1

Question 15.
The volume of a cube in m3 is numerically equal to its surface area in m². The volume of the cube is
(a) 64m³
(b) 1000m³
(c) 216m³
(d) 512m³

Question 16.
The weight of a body is 12g. This statement is not correct because:
(а) the correct symbol for the unit of weight has not been used
(b) the correct symbol for gram is gm.
(c) the weight should be expressed in kg.
(d) None of the above

Answer: (а) the correct symbol for the unit of weight has not been used

Question 17.
Give that the displacement of a particle is given by x = A² sin² kt, where t denotes the time. The unit of k is
(b) metre
(c) hertz
(d) second

Question 18.
Which of the following is the unit of molar gas constant?
(a) JK-1 mol-1
(b) J
(c) JK-1
(d) J mol-1

Answer: (a) JK-1 mol-1

Question 19.
The dimensional formula for angular momentum is same as that for:
(a) torque
(b) Plank’s constant
(c) gravitational constant
(d) impulse

Answer: (b) Plank’s constant

Question 20.
Which of the following physical quantity is dimensionless?
(a) angle
(b) specific gravity
(c) strain
(d) all of these

Answer: (d) all of these

Fill in the blanks

Question 1.
………………. is used to find the distance of a hill indirectly.

Answer: Reflection or ecfio method.

Question 2.
The angle made by the tw o diametrically opposite ends of the moon at a point on Earth is called ………………. and its value for moon is about ……………….

Answer: angular diameter of the moon, 0.5.

Question 3.
The order of magnitude of the mass in kg of man is ………………. electron is ………………. and that of Earth is ……………….

Answer: 2, -30, 25.

Question 4.
Spring balance works on the ………………. law.

Question 5.
A ………………. clock is the most accurate one.

Question 6.
The ……………….. and ………………. masses of an object do BOS differ from each other.

Answer: Inertial and gravitational.

Question 7.
………………. is the dimensional formula of gravitational field strength.

Answer: It M° L T-2J.

Question 8.
The relative accuracy of measurement by a screw gauge can be increased by ……………….

Answer: increasing the number of divisions on the circular scale.

Question 9.
The relative error decreases on increasing the number of divisions on the circular scale because least count ………………. due to it.

Question 10.
Mean value – measured value gives the ……………….

Question 11.
The estimated radius of the universe is of the order of ……………….

True/False Type Questions

Question 1.
The density of water is 1000 kgm-3

Question 2.
106 km is not expressed as M km as the use of double prefixes is not allowed.

Question 3.
The absolute error in each measurement is equal to the least count of the measuring instrument.

Question 4.
The pure numbers have no dimensions Le. they are dimensionless.

Question 5.
A physical quantity may be dimensionless but it may have units.

Question 6.
Frequency and velocity gradient have the same unit.

Question 7.
Impulse and energy gradient have the Same unit.

Question 8.
Surface tension and force gradient have the same unit.

Question 9.
Potential gradient and electric field have the same unit.

Question 10.
Pascal metre is the S*I. unit of energy.

Question 11.
Displacement gradient have the units of length.

Question 12.
All Quantities may be represented dimensionally in terms of the basic quantities.

Question 13.
A basic quantity cannot be represented dimensionally in terms of the other basic or fundamental quantities.

Question 14.
The dimension of a derived quantity is never zero in any fundamental quantity

Question 15.
The dimension of a fundamental quantity in other fundamental quantities is always zero.

Question 16.
A dimensionally correct equation may be correct

Question 17.
A dimensionally incorrect equation may be incorrect

Question 18.
A dimensionally correct equation may be incorrect

Question 19.
A dimensionally incorrect equation may be correct

Question 20.
A quantity can have dimensions but still have no units.

Question 21.
A quantity cap have units but still be dimensionless. Give an example.

Question 22.
Gravitational constant (G), Plank’s constant (h) and Boltzmann constant (k) are constants and have dimensions.

Question 23.
Dimensional formula and dimensional equation are different.

Question 24.
Nm-2 is the unit of force.

 Column I Column II (1) Stress or thrust (a) force (2) Relative density (b) zero error (3) Dimensional formula for the time rate of change of impulse (c) [M° L²T-2] (4) Unit of distance (d) dimensionless quantity (5) Dimensional formula for angular momentum (e) Pressure (6) Instrumental error (f) light year (7) $$\frac { absolute error }{ True value }$$ × 100 (g) never has a non zero dimension (8) Unitless quantity (h) Percentage error (9) Distance between Earth and star (i) Plank’s constant (10) Latent heat (j) Angstrom
 Column I Column II (1) Stress or thrust (e) Pressure (2) Relative density (d) dimensionless quantity (3) Dimensional formula for the time rate of change of impulse (a) force (4) Unit of distance (j) Angstrom (5) Dimensional formula for angular momentum (i) Plank’s constant (6) Instrumental error (b) zero error (7) $$\frac { absolute error }{ True value }$$ × 100 (h) Percentage error (8) Unitless quantity (g) never has a non zero dimension (9) Distance between Earth and star (f) light year (10) Latent heat (c) [M° L²T-2]