CBSE Class 11 Physics Units and Measurements MCQs Set C

Question. The height of a man is 5.87532 ft. But measurement is correct upto three significant figures. The correct height is :
(a) 5.86 ft
(b) 5.87 ft
(c) 5.88 ft
(d) 5.80 ft
Answer: c

Question. One bar is equivalent to 10⁵ N/m². The atmosphere pressure is 1.013 x 10⁵ N/m² . The same in bar is :
(a) 1.88 bar
(b) 1.013 bar
(c) 2.013 bar
(d) none of these
Answer: b

Question. Assuming the length of the day uniformly increases by 0.001 second per century. The net effect on the measure of time over 20 centuries is :
(a) 3.2 hour
(b) 2.1 hour
(c) 2.4 hour
(d) 5 hour
Answer: b

Question. What are dimensions of Young's modulus of elasticity ?
(a) [ML^-1T^-2]
(b) [MLT^-2]
(c) [MLT^-1]
(d) None of these
Answer: a

Question. The value of universal gas constant is R = 8.3 J/kcal/mol. The value of R in atmosphere litre per kelvin/mol is :
(a) 8.12 atm litre/K mol
(b) 0.00812 atm litre/K mol
(c) 81.2 atm litre/K mol
(d) 0.0812 atm litre/K mol
Answer: d

Question. One atomic mass unit in amu = 1.66 x 10^-27 kg. The atomic weight of oxygen is 16. The mass of one atom of oxygen is :
(a) 26.56 x l0^-27kg
(b) 10.53 x l0^-27 kg
(c) 74x l0-²⁷kg
(d) 2.73 x 10^-27 kg
Answer: a

Question. One calorie of heat is equivalent to 4.2 J. One BTU (British thermal unit) is equivalent to 1055 J. The value of one BTU in calorie is :
(a) 251.2 cal
(b) 200 cal
(c) 263 cal
(d) none of these
Answer: a

Question. The area of a room is 10 m² The same in ft² is :
(a) 107.6 feet₂ 
(b) 77 feet²
(c) 77.6 feet²
(d) none of these
Answer: a

Question. In the equation y = a sin (cot + kx), the dimensional formula of co is :
(a) [M°L°T^-1] 
(b) [M°LT^-1]
(c) [ML°T°] 
(d) [M°L^-1 T°]
Answer: a

Question. In the previous question, what is the distance between the centres of adjacent atoms ?
(a) 2.82 x 10 ^-9 m
(b) 0.282 x l0 ^-9 m
(c) 0.63 x 10 ^-9 m
(d) 6.33 x l0 ^-9 m
Answer: b

Question. The electric flux is given by scalar product of electric field strength and area. What are dimensions of electric flux?
(a) [ML³T^-2A^-2]
(b) [ML³T^-2A^-1]
(c) [ML³T^-3A^-1]
(d) [M²LT^-1A⁰]
Answer: a

Question. Electric displacement is given by D = eE
Here, e = electric permittivity
E = electric field strength The dimensions of electric displacement is :
(a) [ML^-2TA]
(b) [L^-2T^-1A]
(c) [L^-2TA]
(d) none of these
Answer: c

Question. The world's largest cut diamond is the first star of Africa (mounted in the British Royal Sculpture and kept in the tower of London). Its volume is 1.84 cubic inch. What is its volume in cubic metre ?
(a) 30.2 x 10^-6 m³
(b) 33.28 m³
(c) 4.8 m³
(d) None of these
Answer: a

Question.1.0x2.88 is equal to :
(a) 2.88
(b) 2,880
(c) 2.9
(d) none of these
Answer: c

Question. A particle starting from the origin (0, 0) moves in a straight line in the (x, y) plane. Its coordinates at a later time are (The path of the particle makes with the x-axis an angle of
(a) 300
(b) 450
(c) 600
(d) 0
Answer: c

Question. Electron volt is a unit of
(a) charge
(b) potential difference
(c) energy
(d) magnetic force
Answer: c

Question. The dimensions of 1/2 eE are same as :
(a) energy density (energy per unit volume)
(b) energy .
(c) power
(d) none of the above
Answer: a

Question. The mass of earth is 5.98 x 10²⁴ kg. The average atomic weight of atoms that make up Earth is 40 u. How many atoms are there in Earth ?
(a) 9 x l0⁵¹
(b) 9 x 10⁴⁹
(c) 9 x l0⁴⁶
(d) 9 x l0⁵⁵
Answer: b

Question. One amu is equivalent to 931 MeV energy. The rest mass of electron is 9.1 x 10^-31 kg. The mass equivalent energy is (Here 1 amu = 1.67 x 10^-27kg)
(a) 0.5073 MeV
(b) 0.693 MeV
(c) 4.0093 MeV
(d) none of these
Answer: a

Question. Electron volt is the unit of energy (1 eV = 1.6 x 10^-19J ). In H-atom, the binding energy of electron in first orbit is 13.6 eV. The same in joule (J) is:
(a) 10 x l0^-19 J
(b) 21.76 x l0^-19 J
(c) 13.6 x 10 ^-19 J
(d) none of these
Answer: b

Question. Crane is British unit of volume, (one crane = 170. 474 litre). Convert crane into SI unit:
(a) 0.170474 m³
(b) 17.0474 m³
(c) 0.0017474 m³
(d) 1704.74 m³
Answer: a

Question. The age of the universe is 5 x 10¹⁷ second. The age of universe in year is :
(a) 158 x 10⁶
(b) 158 x l0⁹
(c) 158 x 10⁸
(d) 158 x 10¹¹
Answer: c

Question. The time between human heart beat is 8 x 10^-1 second. How many heart beats are measured in one minute ?
(a) 75
(b) 60
(c) 82
(d) 64
Answer: a

Question. Light year is a unit of
(a) time
(b) distance
(c) sunlight intensity
(d) mass
Answer: b

Question. In SI system the fundamental units are
(a) meter, kilogram, second, ampere, Kelvin, mole and candela
(b) meter, kilogram, second, coulomb, Kelvin, mole and candela
(c) meter, Newton, second, ampere, Kelvin, mole and candela
(d) meter, kilogram, second, ampere, Kelvin, mole and lux
Answer: b

Question. F energy (E), velocity (v) and force (F) are taken as fundamental quantities, what are the dimensions of mass?
(a) Ev2
(b) Ev -2
(c) Fv -1
(d) Fv -2
Answer: b

Question. The dimensional formula Of the Hall coefficient is:
(a) [M⁰L⁰A^-2T^-1]
(b) [M⁰L³AJ]
(c) [M⁰L⁰ AT]
(d) [M⁰L³A^-1T]
Answer: d

Question.The density of iron is 7.87 g/cm³. If the atoms are spherical and closely packed. The mass of iron atom is 9.27 x 10^-26 kg; What is the volume of an iron atom ?
(a) 1.18 x 10^-29 m³ 
(b) 2.63 x 10^-29 m³
(c) 1.73 x 10^-2S m³
(d) 0.53 x 10^-29 m³
Answer: a

Question. Fundamental or base quantities are arbitrary. In SI system these are
(a) length, force, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity
(b) length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity
(c) as length, mass, time, electric charge, thermodynamic temperature, amount of substance, and luminous intensity
(d) length, mass, force, electric current, thermodynamic temperature, amount of substance, and luminous intensity
Answer: b

Question. The volume of a cube in m³ is equal to the surface area of the cube in m². The volume of the cube is
(a) 64 m³
(b) 216 m³
(c) 512 m³
(d) 196 m³
Answer: b

Question. The radius of hydrogen atom in ground state is 5x10^-11 m. The radius of hydrogen atom in fermi metre is (1 fm = 10^-15 m):
(a) 5 x 10⁴ fm
(b) 2 x 10⁴ fm
(c) 5 x 10² fm
(d) 5 x 10⁶ fm
Answer: a

Question. Unit for a fundamental physical quantity is
(a) defined as best of various reference standards
(b) the smallest measurable value of the physical quantity
(c) defined as average various reference standards
(d) reference standard for the physical quantity
Answer: d