NEET Physics Surface Tension Surface Energy and Capillarity MCQs Set A

a) 2.25 × 10^–2 N

b) 1.5 × 10^–2 N

c) 0.075 N

d) 0.225 N

Answer:  2.25 × 10^–2 N

Question:  A water film is formed between two straight parallel wires of 10 cm length 0.5 cm apart. If the distance between wires is increased by 1 mm. What will be the work done ? (surface tension of water = 72 dyne/cm)

a) 144 erg

b) 72 erg

c) 288 erg

d) 36 erg

Answer: 144 erg

Question:  The work done in increasing the size of a soap film from 10 cm × 6 cm to 10 cm × 11 cm is 3 × 10^–4J. The surface tension of the film is

a) 3 × 10^–2 N/m

b) 11 × 10^–2 N/m

c) 6 × 10^–2 N/m

d) 1.5 × 10^–2 N/m

Answer: 3 × 10^–2 N/m

Question: A mercury drop of radius 1 cm is sprayed into 106 drops of equal size. The energy expressed in joule is (surface tension of Mercury is 460 × 10^–3 N/m)

a) 0.057

b) 5.7

c) 5.7 × 10^–4

d) 5.7 × 10^–6

Answer:  0.057

Question:  Work done in increasing the size of a soap bubble from radius 3 cm to 5 cm is nearly (surface tension of soap solution = 0.03 Nm^–1)

a)

b)

c)

d)

Answer:

Question:

a) 6

b) 8

c) 9

d) 2

Answer:  6

Question:

a) 8

b) 9

c) 7

d) 2

Answer: 8

Question:  A 20 cm long capillary tube is dipped in water. The water rises up to 8 cm. If the entire arrangement is put in a freely falling elevator the length of water column in the capillary tube will be

a) 20 cm

b) 4 cm

c) 8 cm

d) 10 cm

Answer: 20 cm

Question: In a capillary tube, water rises to 3 mm. The height of water that will rise in another capillary tube having one-third radius of the first is

a) 9 mm

b) 6 mm

c) 3 mm

d) 1 mm

Answer: 9 mm

Question:  In a surface tension experiment with a capillary tube water rises upto 0.1 m. If the same experiment is repeated on an artificial satellite, which is revolving around the earth, water will rise in the capillary tube upto a height of

a) full length of the capillary tube

b) 0.98 m

c) 0.2 m

d) 0.1 m

Answer:  full length of the capillary tube

Question:  Water rises in a capillary tube to a certain height such that the upward force due to surface tension is balanced by 7.5 × 10^–4N force due to the weight of the liquid. If the surface tension of water is 6 × 10^–2Nm^–1, the inner circumference of the capillary tube must be

a)  1.25 × 10^–2m

b) 0.50 × 10^–2m

c) 12.5 × 10^–2m

d) 6.5 × 10^–2m

Answer: 1.25 × 10^–2m

Question:  A glass tube of uniform internal radius (r) has a valve separating the two identical ends. Initially, the valve is in a tightly closed position. End 1 has a hemispherical soap bubble of radius r. End 2 has sub-hemispherical soap bubble as shown in figure. Just after opening the valve

a) air from end 1 flows towards end 2. Volume of the soap bubble at end 1 decreases

b) no change occurs

c) air from end 2 flows towards end 1. Volume of the soap bubble at end 1 increases

d) air from end 1 flows towards end 2. No change in the volume of the soap bubbles

Answer: air from end 1 flows towards end 2. Volume of the soap bubble at end 1 decreases

Question:  Radius of a capillary tube is 2 × 10^–3m. A liquid of weight 6.28 × 10^–4 N may remain in the capillary then the surface tension of liquid will be

a) 5 × 10^–2 N/m

b) 50 N/m

c) 5 N/m

d) 5 × 10³ N/m

Answer:  5 × 10^–2 N/m

Question:

a) 2.44 cm

b) 3.12 cm

c) 3.68 cm

d) 1.22 cm

Answer: 2.44 cm

Question:

a)

b)

c)

d)

Answer:

More Questions.....................................

Question: Two capillary tubes A and B of diameter 1 mm and 2 mm respectively are dipped vertically in a liquid. If the capillary rise in A is 6 cm, then the capillary rise in B is

a) 3 cm

b) 4 cm

c) 6 cm

d) 2 cm

Answer: 3 cm

Question:  Water rises to a height of 10 cm in capillary tube and mercury falls to a depth of 3.1 cm in the same capillary tube. If the density of mercury is 13.6 and the angle of contact for mercury is 135°, the approximate ratio of surface tensions of water and mercury is

a) 1 : 6

b) 1.5 : 1

c) 1 : 3

d) 1 : 0.15

Answer: 1 : 6

Question:  In a capillary rise experiment, the water level rises to a height of 5 cm. If the same capillary tube is placed in water such that only 3 cm of the tube projects outside the water level, then

a) angle of contact increases

b) the meniscus completely vanishes

c) angle of contact decreases

d) water will begin to overflow through the capillary

Answer:  angle of contact increases

Question:  The surface tension of water is 75 dyne/cm. Find the minimum vertical force required to pull a thin wire ring up (refer figure) if it is initially resting on a horizontal water surface. The circumference of the ring is 20 cm and its weight is 0.1 N :

a) 0.130 N

b) 0.115 N

c) 0.225 N

d) 0.125 N

Answer:  0.130 N

Question:

a)

b)

c)

d) None of these

Answer:

Question: Surface tension of a liquid is due to

a) cohesive force between molecules

b) adhesive force between molecules

c) electrical force between molecules

d) gravitational force between molecules

Answer: cohesive force between molecules

Question:  If a soap bubble formed at the end of the tube is blown very slowly, then the graph between excess pressure inside the bubble with time will be a

a) parabolic curve sloping down

b) parabolic curve sloping up

c) straight line sloping down

d) straight line sloping up

Answer: parabolic curve sloping down

Question:  Surface tension may be defined as

a) the work done per unit area in increasing the surface area of a liquid under isothermal conditions

b) the work done per unit area in increasing the surface area of a liquid under adiabatic conditions

c) the work done per unit area in increasing the surface area of a liquid under adiabatic conditions

d) free surface energy per unit volume

Answer:  the work done per unit area in increasing the surface area of a liquid under isothermal conditions

Question:  Which of the following graph represents the variation of surface tension with temperature over small temperature ranges for water?

a)

b)

c)

d) None of these

Answer:

Question:  If a water drop is kept between two glass plates, then its shape is

a)

b)

c)

d) None of these

Answer:

Question:

a)

b)

c)

d)

Answer:

Question:

a)

b)

c)

d)

Answer:

Question:  At critical temperature, the surface tension of a liquid is

a) zero

b) infinity

c) the same as that at any other temperature

d) None of these

Answer:  zero

Question:   If two soap bubbles of different radii are in communication with each other then

a) air flows from the smaller bubble into the larger one and the larger one grows at the expense of the smaller one

b) the air flows from the larger into the smaller bubble until the radius of the smaller one becomes equal to that of the larger one and of the larger one equal to that of the smaller one.

c) the size of the bubbles remains the same

d) air flows from the larger bubble into the smaller one until the two bubbles are of equal size

Answer: air flows from the smaller bubble into the larger one and the larger one grows at the expense of the smaller one

Question:  Two water droplets merge with each other to form a larger droplet. In this process

a) energy is liberated

b) energy is absorbed

c) energy is neither liberated nor absorbed

d) some mass is converted into energy

Answer: energy is liberated

Question:  Consider the following statements and select the true statement(s)?
I. A large soap bubble shrinks while a small soap bubble expands when they are connected to each other by a capillary tube, in order to gain equilibrium
II. The raindrops fall on the surface of earth with the same constant velocity
III. A hydrogen filled balloon stops rising after it has attained a certain height in the sky

a) III only

b) I & III

c) II only

d) I only

Answer:  III only

Question:

a)

b)

c)

d)

Answer:

Question:  For a given volume which of the following will have minimum energy?

a) Sphere

b) Cube

c) Cone

d) All have same energy

Answer: Sphere

Question:  Which of the following expressions represents the excess of pressure inside the soap bubble?

a)

b)

c)

d) None of these

Answer:

Question:  The lower end of a capillary tube of radius r is placed vertically in water. Then, with the rise of water in the capilllary , heat evolved is :

a)

b)

c)

d)

Answer:

Question:  When a pinch of salt or any other salt which is soluble in water is added to water, its surface tension

a) increases

b) decreases

c) may increase or decrease depending upon salt

d) None of these

Answer: increases

Question: If more air is pushed in a soap bubble, the pressure in it

a) becomes zero

b) increases

c) decreases

d) remains same

Answer:  becomes zero

Question: A drop of oil is placed on the surface of water. Which of the following is correct?

a) It will spread as a thin layer

b) It will partly be a spherical droplet and partly a thin film

c) It will float as a distorted drop on the water surface

d) It will remain on it as a sphere

Answer: It will spread as a thin layer

Question: Kerosene oil rises up in a wick of a lantern because of

a) capillary action

b) buoyant force of air

c) the gravitational pull of the wick

d) diffusion of the oil through the wick

Answer: capillary action

Question: Assertion : Surface tension of all lubricating oils and paints is kept high.
Reason : Due to high value of surface tension the fluids don't get damaged.

a) Assertion is incorrect, reason is correct

b) Assertion is correct, reason is incorrect

c) Assertion is correct, reason is correct; reason is not a correct explanation for assertion

d) Assertion is correct, reason is correct; reason is a correct explanation for assertion

Answer:  Assertion is incorrect, reason is correct

Question:  With the increase in temperature, the angle of contact

a) decreases

b) increases

c) remains constant

d) sometimes increases and sometimes decreases

Answer: decreases

Question: Due to capillary action, a liquid will rise in a tube if angle of contact is

a) acute

b) obtuse

c) 90º

d) zero

Answer:  acute

Question:  Select the false statement(s) about surface tension from the following?
I. Surface tension is the extra energy that the molecules at the interface have as compared to the molecules in the interior
II. The value of surface tension is independent of the temperature
III. Surface tension causes capillary action

a) II only

b) I & II

c) I, II & III

d) I only

Answer: II only

Question: A glass capillary tube of inner diameter 0.28 mm is lowered vertically into water in a vessel. The pressure to be applied on the water in the tube so that water level in the tube is same as that in the vessel in N/m² is (surface tension of water = 0.07 N/m, atmospheric pressure = 10⁵ N/m²)

a) 99 × 10³

b) 100 × 10³

c) 101 × 10³

d) 10³

Answer: 99 × 10³

Question: Assertion : Smaller the droplets of water, spherical they are.
Reason : Force of surface tension is equal, and opposite to force of gravity.

a) Assertion is correct, reason is incorrect

b) Assertion is incorrect, reason is correct

c) Assertion is correct, reason is correct; reason is not a correct explanation for assertion

d) Assertion is correct, reason is correct; reason is a correct explanation for assertion

Answer:  Assertion is correct, reason is incorrect