# Surface  tension mcq Pdf

1. Surface Tension is defined as force per unit length of imaginary line drawn on free surtace of liquid at right angles on either side of line.
2. The film at the top of liquid surface having thickness equal to molecular range is caled surface film.
3. The potential energy per unit area of liquid surface is known as surface energy.
4. For a liquid in contact with solid, angle between surface of solid and tangent drawn to the free surface of liquid at the point of contact measured from the side of liquid is called angle of contact of that solid liquid pair.
5. Angle of contact is zero, when liquid wets solid completely.
6. Angle of contact is acute, whin liquid wets the solids partially
7. Angle of contact is obtuse, when liquid does not wet the solid.

Surface tension MCQs questions and answers are provided here with answers and detailed explanation each question. These Surface tension MCQs are important from the NEET as well as various type of exam. By practicing our Mcq on surface tension pdf students will get acquainted with the key concepts which must be prepared to score high marks in the objective type questions in the any exam.

## Surface Tension MCQs For  NEET

1. The dimensional formula of surface tension is__________
(a) [M L-¹ T-²]
(b) [M L²T-²]
(c) [M L T-¹]
(d) [M L⁰ T-²]

2. Rain drops are spherical in nature because of__________
(a) capillarity
(b) acceleration due to gravity
(c) surface tension
(d) viscosity

3. Two drops of a liquid are merged to form a single drop. In this process________
(a) energy is absorbed
(b) energy 1s released
(c)energy remains constant
(d) energy becomes half

4. If a surface is contaminated, then the surface tension________
(a) increases
(b) decreases
(c) does not change
(d) becomes zeroo

5. Washing soap is used for cleaning the clothes, because______
(a) it absorbs dirt
(b) it increases the surface tension of the solution
(c)it reduces the surface tension of the solution
(d) it increases the viscosity of the liquid

6. The phenomenon of surface tension is due to_______
(b) gravitational force
(c) intermolecular cohesive force
(d) nuclear force

7. If a detergent is dissolved in water, the surface tension of water_____
(a) remains constant
(b) increases
(c) decreases
(d) becomes zero

8. Cohesion is maximum in_______
(a) solids
(b) liquids
(c) gases
(d) same in all

9. If common salt is dissolved in water, then the S.T. of  Salt water is_______

(a) increased

(b) decreased

(c) not changed

(d) first decreases and then increases

10. Water rises upto a height of 4 cm, in a capillary tube, if the tube is immersed vertically in water. What will be the length of water column in the capillary tube, if the tube is immersea in water, at an angle of 60° with the vertical?

(a) 4 cm

(b) 6 cmn

(c) 8 cm

(d) 2 cm

11. The angle of contact between a glass capillary tube of length 10 cm and a liquid is 90°. If the capillary tube is dipped vertically in the liquid, then the liquid_________

(a) will rise in the tube

(b) will get depressed in the tube

(c) will rise upto. 10 cm in the tube and will over flow

(d) will neither rise nor fall in the tube

12. At the boiling point of water, its surface tension_______

(a) is infinite

(b) is zero

(c) Is the same as that at room temperature

(d) is maximum

13. A liquid is kept in a glass beaker. Which molecules of the liquid have the highest potential energy ?

(a) molecules at the bottom of the breaker

(b) molecules near the centre of the liquid

(c)molecules lying at half the depth of the liquid and touching the walls of the beaker

(d) molecules lying in the surface film

14.. Surface tension of liquid is independent of the________

(a) temperature of the liquid

(b) area of the liquid surface

(c) nature of the liquid

(d) impurities present in the liquid

15.. The angle of contact between a glass capillary tube of length 10 cm and a liquid is 90. If the capillary tube is dipped vertically in the liquid, then the liquid___________

(a) will rise in the tube

(b) will get depressed in the tube

(c) will rise upto. 10 cm in the tube and will over flow

(d) will neither rise nor fall in the tube

16. At the boiling point of water, its surface tension_________

(a) is infinite

(b) is zero

(c) 1s the same as that at room temperature

(d) is maximum

17. For tap water and clean glass, the angle of contact is________
(a) 0°
(b) 90°
(c) 140°
(d) 8°

18. Choose the wrong statement from the following.
(a) Small droplets of a liquid are spherical due to surface tension
(b) Oil rises through the wick due to capillarity
(c) In drinking the cold drinks through a straw, we use the phenomenon of capillarity
(d) Gum is used to stick two surfaces. In this process we use the property of Adhesion

19. The work done in blowing a soap bubble of radius R is W and that to a radius 3R is W2 The ratio of work done is_________
(a) 1:3
(b) 3:1
(c) 1:9
(d) 9:1

20. When the angle of contact between a solid and a liquid is 90, then_______
(a) Cohesive force > Adhesive force
(b) Cohesive force < Adhesive force
(c) Cohesive force = Adhesive force
(d) Cohesive force >> Adhesive force

21. For a liquid, which is rising in a capillary tube, the angle of contact is________
(a) 900
(b) 1800
(c) Acute
(d) Obtuse

22. Out of the following, which one is not an example of capillary action______
(a) ploughing of the field
(b) absorption of ink in a blotting paper
(c) floating of wood on the surface of water
(d) rise of oil in the wick of a lamp

23. A liquid is kept in a glass vessel. If the liquid solid adhesive force between the liquid and the vessel is very weak as compared to the cohesive force in the liquid, then the shape of the liquid surface near the solid should be_______
(a) Convex
(b) Concave
(c) Almost vertical
(d) Horizontal

24. An imaginary sphere drawn around a molecule as centre, with a radius equal to the range of molecular attraction is_________

(a) surface film

(b) range of molecular attraction

(c) sphere of influence

25. Surface tension is equal to_________

a) free surface energy per unit area

b) pressure per unit volume

c) force per unit area

d) none of these

26. The potential energy of the molecules on the free surface of a liqud is ________

(a) minimum

(b) maximum

(c) zero

(d) infinity

27. The unit of surtace tension is________

(a) N-¹m-¹

(b) Nm-¹

(c)N-¹M

(d) Nm

28. A shaving brush is dipped in water. When it is taken out of water, the hairs in the brush cling together. This is because of__________

(a) attraction between the hairs

(b) surface tension

(c) gravity

(d) Viscosity

29. When the temperature of a liquid is increased, the surface tension of the liquid_______

(a) increases

(b) decreases

(c) does not change

(d) sometime increases and sometime decreases

30. 10 water drops merge to form a single drop. In this process________

(a) energy is absorbed

(b) energy is liberated

(c) energy is neither absorbed nor liberated

(d) total surface area increases

31. An imaginary line is a drawn in a liquid surface. At whatcangle with the line, the surface tension acts?

(a) 0

(b) 45°

(c) 180°

(d) 90°

32. Molecular forces are_______

(a) Always repulsive

(b) Always attractive

(c) Sometimes attractive and sometimes repulsive depending upon the nature of the molecules

(d) Attractive upto a certain distance and for larger distances they are repulsive

33. A spherical mercury drop is broken into 1000 droplets, all of the same size. In this process, the physical quantity that does not change is its__________

(a) surface energy