NEET Physics Units and Measurement MCQs Set A

Question. The sum of the numbers 436.32, 227.2 and 0.301 in appropriate significant figures is
(a) 664
(b) 663.8
(c) 663.82
(d) 663.821

Answer: A

Question. The mass and volume of a body are 4.237 g and 2.5 cm3, respectively. The density of the material of the body in correct significant figures is
(a) 1.7 g cm^–3
(b) 1.6048 g cm^–3
(c) 1.69 g cm^–3
(d) 1.695 g cm^–3

Answer: A

Question. The numbers 2.745 and 2.735 on rounding off to 3 significant figures will give
(a) 2.74 and 2.74
(b) 2.74 and 2.73
(c) 2.75 and 2.74
(d) 2.75 and 2.73

Answer: A

Question. The length and breadth of a rectangular sheet are 16.2 ± 0.1 cm and 10.1 ± 0.1 cm, respectively. The area of the sheet in appropriate significant figures and error is
(a) 164 ± 3 cm²
(b) 163.6 ± 2.6 cm²
(c) 163.62 ± 2.6 cm²
(d) 163.62 ± 3 cm²

Answer: A

Question. Which of the following pairs of physical quantities does not have same dimensional forrmula?
(a) Tension and surface tension
(b) Impulse and linear momentum
(c) Angular momentum and Planck's constant
(d) Work and torque

Answer: A

Question.  Measure of two quantities along with the precision of respective measuring instrument is A = 2.5 ms^–1 ± 0.5 ms^–1, B = 0.10 s ± 0.01 s. The value of AB will be
(a) (0.25 ± 0.08) m
(b) (0.25 ± 0.05) m
(c) (0.25 ± 0.5) m
(d) (0.25 ± 0.135) m

Answer: A

Question.  Which of the following measurement is most precise?
(a) 5.00 mm
(b) 5.00 m
(c) 5.00 cm
(d) 5.00 km

Answer: A

Question.  The mean length of an object is 5 cm. Which is the following measurement is most accurate?
(a) 4.9 cm
(b) 5.25 cm
(c) 4.805 cm
(d) 5.4 cm

Answer: A

Question. Young's modulus of steel is 1.9 × 10¹¹ N/m². When expressed in CGS units of dyne/cm², it will be equal to (1N = 10⁵ dyne, 1 m² = 10₄ cm2)
(a) 1.9 × 10¹²
(b) 1.9 × 10¹³
(c) 1.9 × 10¹¹
(d) 1.9 × 10¹⁰

Answer: A

Question.  If momentum (p), area (A) and time (T) are taken to be fundamental quantities, then energy has the dimensional formula
(a) [pA^1/2T^–1]
(b) [pA^1/2T]
(c) [p²AT]
(d) None of these

Answer: A

Question. If force (F), velocity (V) and time (T) are taken as fundamental units, then the dimensions of mass are
(a) [F V^–1 T]
(b) [F V T^–2]
(c) [F V T^–1]
(d) None of these

Answer: A

Question. A student measured the length of a rod and wrote it as 3.50 cm. Which instrument did he use to measure it?
(a) A vernier calliper where the 10 divisions in vernier scale matches with 9 divisions in main scale and main scale has 10 division in 1 cm.
(b) A screw gauge having 100 divisions in the circular scale and pitch as 1 mm.
(c) A meter scale.
(d) A screw gauge having 50 divisions in the circular scale and pitch as 1 mm.

Answer: A

Question.  The current voltage relation of diode is given by I = (e^1000V/T –1) mA, where the applied voltage V is in volt and temperature T is in kelvin. If a student makes an error measuring ± 0.01 V while measuring the current of 5 mA at 300 K, what will be the error in the value of current in mA?
(a) 0.2 mA
(c) 0.5 mA
(d) 0.05 mA

Answer: A

Question.  The least count of a stop watch is 0.2 second. The time of 20 oscillations of a pendulum is measured to be 25 second. The percentage error in the measurement of time will be
(a) 0.8%
(b) 0.1%
(c) 1.8%
(d) 8%

Answer: A

Question. Assertion : The number of significant figures depends on the least count of measuring instrument.
Reason : Significant figures define the accuracy of measuring instrument.
(a) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(b) Assertion is correct, reason is incorrect
(c) Assertion is incorrect, reason is correct
(d) Assertion is correct, reason is correct; reason is a correct explanation for assertion

Answer: A

Question.  A screw gauge with a pitch of 0.5 mm and a circular scale with 50 divisions is used to measure the thickness of a thin sheet of Aluminium. Before starting the measurement, it is found that when the two jaws of the screw gauge are brought in contact, the 45th division coincides with the main scale line and the zero of the main scale is barely visible. What is the thickness of the sheet if the main scale reading is 0.5 mm and the 25th division coincides with the main scale line?
(a) 0.80 mm
(b) 0.75 mm
(c) 0.50 mm
(d) 0.70 mm

Answer: A

Question.  A student measures the time period of 100 oscillations of a simple pendulum four times. The data set is 90 s, 91 s, 95 s, and 92 s. If the minimum division in the measuring clock is 1 s, then the reported mean time should be
(a) 92 ± 2 s
(b) 92 ± 1.8 s
(c) 92 ± 3s
(d) 92 ± 5.0 s

Answer: A

Question.  A force F is applied onto a square plate of side L. If the percentage error in determining L is 2% and that in F is 4%, the permissible percentage error in determining the pressure is
(a) 8%
(b) 6%
(c) 4%
(d) 2%

Answer: A

Question. Assertion: In the measurement of physical quantities direct and indirect methods are used.
Reason : The accuracy and precision of measuring instruments along with errors in measurements should be taken into account, while expressing the result.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct

Answer: A

Question.  A student measured the diameter of a small steel ball using a screw gauge of least count 0.001 cm. The main scale reading is 5 mm and zero of circular scale division coincides with 25 divisions above the reference level. If screw gauge has a zero error of –0.004 cm, the correct diameter of the ball is
(a) 0.529 cm
(b) 0.053 cm
(c) 0.525 cm
(d) 0.521 cm

Answer: A

Question.  The density of a material in the shape of a cube is determined by measuring three sides of the cube and its mass. If the relative errors in measuring the mass and length are respectively 1.5% and 1%, the maximum error in determining the density is:
(a) 4.5%
(b) 6%
(c) 3.5%
(d) 2.5%

Answer: A

Question.  The moment of inertia of a body rotating about a given axis is 6.0 kg m2 in the SI system. What is the value of the moment of inertia in a system of units in which the unit of length is 5 cm and the unit of mass is 10 g?
(a) 2.4 × 10⁵
(b) 6.0 × 10³
(c) 6.0 × 10⁵
(d) 2.4 × 10³

Answer: A

Question. The relative uncertainty in the period of a satellite orbiting around the earth is 10^–2. If the relative uncertainty in the radius of the orbit is negligible, the relative uncertainty in the mass of the earth is
(a) 2 × 10^–2
(b) 6 × 10^–2
(c) 10^–2
(d) 3× 10^–2

Answer: A

Question.  The _____ is a measure of how closed the measured value is to the true value of quantity.
(a) accuracy
(b) Precision
(c) Both
(d) None of these

Answer: A

Question.  The smallest value that can be measured by the measuring instrument is called
(a) least count
(b) parallax
(c) Both
(d) None of these

Answer: A

Question.  The ratio of the dimensions of Planck’s constant and that of the moment of inertia is the dimensions of
(a) None of these
(b) time
(c) angular momentum
(d) velocity

Answer: A

Question. The dimensions of pressure is equal to
(a) energy per unit volume
(b) energy
(c) None of these
(d) force per unit volume

Answer: A