CBSE Class 11 Physics MCQs Set 14

Question. Intermolecular forces are attractive when the separation of molecules is...
[A] more than the equilibrium separation
[B] less than the equilibrium separation
[C] equal to the equilibrium separation
[D] zero
Answer: A

Question. The inter atomic potential is dependent on...
[A] the shape of the atoms only
[B] the distance between the atoms only
[C] both the shape and the distance between the atoms
[D] none of above
Answer: B

Question. The shear stress that acts on an object affects its...
[A] length
[B] width
[C] volume
[D] shape
Answer: D

Question. The only elastic modulus that applies to liquids is...
[A] Young's modulus
[B] Shear modulus
[C] modulus of rigidity
[D] bulk modulus
Answer: D

Question. In the steady flow, the streamlines...
[A] do not exist
[B] are fixed in number
[C] intersect one another
[D] do not intersect one another
Answer: D

Question. If the radius of a pipe is increased by 50%, the fluid velocity v becomes...
[A] (3/2).v
[B] (2/3).v
[C] (4/9).v
[D] (9/4).v
Answer: D

Question. The average speed of the molecules in a bottle of gas at pressure P and absolute temperature T is doubled. The new pressure and temperature are, respectively...
[A] 2P, 2T
[B] 4P, 4T
[C] 4P, 2T
[D] 2P, 4T
Answer: C

Question. In the equation, PV = constant, the value of the constant depends on...
[A] the temperature of the gas
[B] the mass of the gas
[C] the temperature and the mass of the gas
[D] the temperature and the pressure of the gas
Answer: B

Question. For water, triple point occurs at...
[A] 76 mmHg, 273.16K
[B] 76 mmHg, 273.16°C
[C] 4.58 mmHg, 273.16K
[D] 4.58 mmHg, 273.16°C
Answer: C

Question. The density of water is maximum at...
[A] 0°C
[B] 4°C
[C] 30°C
[D] 32°F
Answer: C

Question. Dipole moment is...
[A] a scalar
[B] a vector from -q to +q
[C] a vector from +q to -q
[D] a vector perpendicular to the distance vector
Answer: B

Question. If an ebonite rod is rubbed with fur...
[A] the rod gets electrified
[B] the fur gets electrified
[C] both the fur and the rod get electrified
[D] none gets electrified
Answer: B

Question. For a magnet placed in a magnetic field, the maximum torque occurs when the axis of the magnet is...
[A] perpendicular to the field
[B] parallel to the field
[C] inclined at 45° to the field
[D] inclined at 180° to the field
Answer: C

Question. Optical fibres use the principle of...
[A] refraction
[B] total internal refraction
[C] total internal reflection
[D] total internal absorption
Answer: A

Question. When light travels in different materials...
[A] the wavelength remains constant
[B] the frequency remains constant
[C] the velocity remains constant
[D] none of three remains constant
Answer: C

Question. If a star A is two magnitudes brighter than star B, we say that A is _____ times brighter than B.
[A] 2
[B] 2 x 2.512
[C] 2.512 x 2.512
[D] 100
Answer: B

Question. If λ is emitted wavelength, λ is measured wavelength and Z is the displacement of spectral line, then...
[A] Z = (λ - λ)/λ
[B] Z = (λ - λ)/λ 
[C] λ = λ (Z + 1)
[D] λ = λ(Z + 1)
Answer: C

Question. The magnitude of vector 2i - 3j + √ 3.k is...
[A] 2
[B] 3
[C] √ 2
[D] 4
Answer: C

Question. The M.I. of a disc about an axis passing through its centre and perpendicular to its plane is 100 gm.cm². Then, its M.I. about its diameter is...
[A] 100 gm.cm² 
[B] 50 gm.cm² 
[C] 200 gm.cm² 
[D] 25 gm.cm2
Answer: D

Question. A ring , a disc and a sphere, all of same mass and radius, rotate with the same angular velocity about their diameter. Which has maximum rotational kinetic energy?
[A] Ring
[B] Disc
[C] Sphere
[D] All have same kinetic energy
Answer: B

Question. If the earth stops rotating, the value of 'g' will...
[A] increase
[B] decrease
[C] not change
[D] become zero
Answer: A

Question. A parrot resting on a floor of an air-tight box, which is being carried by a girl starts flying. The girl will feel that the box...
[A] is now lighter
[B] is now heavier
[C] shows no change in weight
[D] is also flying
Answer: A

Question. The thermal resistance of a metal block of length l, area of cross-section A and thermal conductivity k is...
[A] l/(k.A)
[B] l.A/k
[C] k.A/l
[D] k.l/A
Answer: C

Question. The equivalent thermal conductivity of a slab consisting of two parallel layers of two different materials of thermal conductivity K₁ and K₂ is...
[A] K₁ + K₂ 
[B] K₁.K₂ 
[C] (K₁ + K₂)/2
[D] (2K₁ + K₂)/(K₁ + K₂)
Answer: A

Question. A sphere, a cube and a thin circular plate, all made of same material and of same mass are heated to a temperature of 100°C. Which of these cools faster when left in air at room temperature?
[A] Sphere
[B] Circular plate
[C] Cube
[D] All of them at the same rate
Answer: B

Question. No energy is transmitted in a...
[A] longitudinal progressive wave
[B] stationary wave
[C] transverse progressive wave
[D] electromagnetic wave
Answer: B

Question. The velocity of sound in air is V. At what speed a source must travel towards a listener at rest so that the apparent frequency heard is double the true frequency of the source?
[A] V/2
[B] V/4
[C] 2V
[D] 4V
Answer: A

Question. A spring with force constant k is cut in half. Each of the new springs has a force constant of...
[A] k/2
[B] k
[C] 2k
[D] √ 2.k
Answer: C

Question. A harmonic oscillator of mass 40 g has a period of 10 seconds. To reduce the period to 5 seconds, the mass should be changed to...
[A] 10 g
[B] 20 g
[C] 80 g
[D] 160 g
Answer: A

Question. An example of a purely longitudinal wave is...
[A] a sound wave
[B] an electromagnetic wave
[C] a water wave
[D] a wave in a stretched string
Answer: D