# MCQs for Physics Class 11 with Answers Chapter 10 Mechanical Properties of Fluids

Students of class 11 Physics should refer to MCQ Questions Class 11 Physics Mechanical Properties of Fluids with answers provided here which is an important chapter in Class 11 Physics NCERT textbook. These MCQ for Class 11 Physics with Answers have been prepared based on the latest CBSE and NCERT syllabus and examination guidelines for Class 11 Physics. The following MCQs can help you to practice and get better marks in the upcoming class 11 Physics examination

## Chapter 10 Mechanical Properties of Fluids MCQ with Answers Class 11 Physics

MCQ Questions Class 11 Physics Mechanical Properties of Fluids provided below have been prepared by expert teachers of grade 11. These objective questions with solutions are expected to come in the upcoming Standard 11 examinations. Learn the below provided MCQ questions to get better marks in examinations.

Question. The cylindrical tube of a spray pump has a cross-section of 6 cm2 one of which has 50 holes each of diameter 1 mm. If the liquid flow inside the tube is 1.2 m per minute, then the speed of ejection of the liquid through the holes is
(a) 2.1 m s–1
(b) 0.31 m s–1
(c) 0.96 m s–1
(d) 3.4 m s–1

B

Question. A capillary tube is taken from the earth to the surface of the moon. The rise of the liquid column on the moon, if acceleration due to gravity on the earth is 6 times that of the moon, is
(a) six times that on the earth’s surface
(b) 1/6 that on the earth’s surface
(c) equal to that on the earth’s surface
(d) zero.

A

Question. Two capillaries of same length and radii in the ratio 1 : 2 are connected in series. A liquid flows through them in streamlined condition. If the pressure across the two extreme ends of the combination is 1 m of water, the pressure difference across first capillary is
(a) 9.4 m
(b) 4.9 m
(c) 0.49 m
(d) 0.94 m

D

Question. The force acting on a window of area 50 cm × 50 cm of a submarine at a depth of 2000 m in an ocean, the interior of which is maintained at sea level atmospheric pressure is
(Density of sea water = 103 kg m–3, g = 10 m s–2)
(a) 5 × 105 N
(b) 25 × 105 N
(c) 5 × 106 N
(d) 25 × 106 N

C

Question. If W1 be the work to be done to form a bubble of volume V from a given solution. The work required to be done to form a bubble of volume 2 V is
(a) 42/3 W1
(b) 41/3 W1
(c) 21/2 W1
(d) 23/2 W1

B

Question. A metallic sphere of mass M falls through glycerine with a terminal velocity v. If we drop a ball of mass 8M of same metal into a column of glycerine, the terminal velocity of the ball will be
(a) 2v
(b) 4v
(c) 8v
(d) 16v

B

Question. The radii of two columns in a U tube are r1 and r2. When a liquid of density r (angle of contact is 0°) is filled in it, the difference in levels of liquid in two arms is h. The surface tension of liquid is (g = acceleration due to gravity)

A

Question. A water barrel stands on a table of height h. If a small hole is punched in the side of the barrel at its base, it is found that the resultant stream of water strikes the ground at a horizontal distance R from the table. What is the depth of water in the barrel?
(a) R2/h
(b) R2/2h
(c) R2/4h
(d) 4R2/h

C

Question. A piece of solid weighs 120 g in air, 50 g in water and 60 g in a liquid. The relative density of the solid and that of the liquid are respectively
(a) 2, 1/2
(b) 2, 3/2
(c) 3, 1/2
(d) 3, 3/2

D

Question. A metal ball B1 (density 3.2 g cm–3) is dropped in water while another metal ball B2 (density 6.0 g cm–3) is dropped in a liquid of density 1.6 g cm–3. If both the balls have the same diameter and attain the same terminal velocity, the ratio of viscosity of water to that of the liquid is
(a) 2.0
(b) 0.5
(c) 4.0
(d) indeterminate due to insufficient data

B

Question. A horizontal pipe line carries water in a streamline flow. At a point along the pipe where the cross sectional area is 10 cm2, the water velocity is 1 m/s and the pressure is 2000 Pa. What is the pressure of water at another point when the cross-sectional area is 5 cm2?
(a) 200 Pa
(b) 300 Pa
(c) 400 Pa
(d) 500 Pa

D

Question. Water rises in a capillary tube to a height of 2.0 cm. In another capillary tube whose radius is one-third of it, how much the water will rise?
(a) 5 cm
(b) 3 cm
(c) 6 cm
(d) 9 cm

C

Question. Eight drops of water, each of radius 2 mm are falling through air at a terminal velocity of 8 cm s–1. If they coalesce to form a single drop, then the terminal velocity of combined drop will be
(a) 32 cm s–1
(b) 30 cm s–1
(c) 28 cm s–1
(d) 24 cm s–1

A

Assertion & Reasoning Based MCQs :

Assertion (A) and the other labelled
Reason (R) Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below.
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true but R is NOT the correct explanation of A
(c) A is true but R is false
(d) A is false and R is also false

Question. Assertion (A) : A man sitting in a boat which is floating on a pond. If the man drinks some water from the pond, the level of the water in the pond remain unchanged.
Reason (R) : According to Archimedes’ principle the weight of water displaced by body is equal to the weight of the body, if the body is floating.

A

Question. Assertion (A) : When height of a tube is less than liquid rise in the capillary tube, the liquid does not overflow.
Reason (R) : Product of radius of meniscus and height of liquid in the capillary tube is always one.

C

Question. Assertion (A) : The viscosity of liquid decreases rapidly with rise of temperature.
Reason (R) : Viscosity of a liquid is the property of the liquid by virtue of which it opposes the relative motion amongst its different layers.

B

Question. Assertion (A) : The size of the needle of a syringe controls flow rate better than the thumb pressure exerted by a doctor while administering an injection.
Reason (R) : Flow rate is independent of pressure exerted by the thumb of the doctor.

C

Question. Assertion (A) : To float, a body must displace liquid whose weight is equal to the actual weight of the body.
Reason (R) : The body will experiences no net downward force, in the case of floating.

B

Question. Assertion (A) : For a floating body to be in stable equilibrium, its centre of buoyancy must be located above the centre of gravity.
Reason (R) : The torque required by the weight of the body and the upthrust will restore body back to its normal position, after the body is disturbed.

A

Question. Assertion (A) : The blood pressure in humans is greater at the feet than at the brain.
Reason (R) : Pressure of liquid at any point is proportional to height, density of liquid and acceleration due to gravity.

A

Question. Assertion (A) : The impurities always decrease the surface tension of a liquid.
Reason (R) : The change in surface tension of the liquid depends upon the degree of contamination of the impurity.

A

Question. Assertion (A) : A fluid flowing out of a small hole in a vessel apply a backward thrust on the vessel.
Reason (R) : According to equation of continuity, the product of area and velocity remain constant.

A

Case Based MCQs :

The property due to which the free surface of liquid tends to have minimum surface area and behaves like a stretched membrane is called surface tension. It is a force per unit length acting in the plane of interface between the liquid and the bounding surface i.e., S = F/L , where F = force acting on either side of imaginary line on surface and L = length of imaginary line.
Surface tension decreases with rise in temperature. Highly soluble impurities increases surface tension and sparingly soluble impurities decreases surface tension.

Question. Which of the following statements is correct?
(a) Viscosity is a vector quantity.
(b) Surface tension is a vector quantity.
(c) Reynolds number is a dimensionless quantity.
(d) Angle of contact is a vector quantity.

C

Question. Which of the following statements is not true about surface tension?
(a) A small liquid drop takes spherical shape due to surface tension.
(b) Surface tension is a vector quantity.
(c) Surface tension of liquid is a molecular phenomenon.
(d) Surface tension of liquid depends on length but not on the area.

B

Question. A liquid does not wet the solid surface if the angle of contact is
(a) 0°
(b) equal to 45°
(c) equal to 90°
(d) greater than 90°

D

Question. The excess pressure inside a soap bubble is three times than excess pressure inside a second soap bubble, then the ratio of their surface area is
(a) 9 : 1
(b) 1 : 3
(c) 1 : 9
(d) 3 : 1

C

Question. Which of the following statement is not true about angle of contact?
(a) The value of angle of contact for pure water and glass is zero.
(b) Angle of contact increases with increase in temperature of liquid.
(c) If the angle of contact of a liquid and a solid surface is less than 90°, then the liquid spreads on the surface of solid.
(d) Angle of contact depend upon the inclination of the solid surface to the liquid surface.

D

It states that for the streamline flow of an ideal liquid through a tube, the total energy (the sum of pressure energy, the potential energy and kinetic energy) per unit volume remains constant at every cross-section throughout the tube.

If the liquid is flowing through a horizontal tube, then h is constant, then according to Bernoulli’s theorem,
P/pg + 1/2 v2/g = constant
Bernoulli’s theorem is based on law of conservation of energy.

Question. Applications of Bernoulli’s theorem can be seen in
(a) dynamic lift of aeroplane
(b) hydraulic press
(c) helicopter
(d) none of these

A

Question. A tank filled with fresh water has a hole in its bottom and water is flowing out of it. If the  size of the hole is increased, then
(a) the volume of water flowing out per second will decrease
(b) the velocity of outflow of water remains unchanged
(c) the volume of water flowing out per second remains zero
(d) Both (b) and (c)

B

Question. Bernoulli’s equation for steady, non-viscous, incompressible flow expresses the
(a) conservation of linear momentum
(b) conservation of angular momentum
(c) conservation of energy
(d) conservation of mass