The contact angle determines whether liquid will rise or get depressed along a solid surface. Select the correct statement regarding the same.

If contact angle is found to be greater than 90 , then liquid will have depressed along the solid surface

If contact angle is found to be less than 90 , the liquid will have raise along the solid surface

If contact angle is found to be greater than 90 , then liquid will have depressed along the solid surface

Liquid always rises along solid surface, irrespective of contact angle

Liquid always gets depressed along solid surface, irrespective of contact angle

Surface energy is ________________

kinetic energy of the surface molecules

the force per unit length acting on surface particles

the energy of the molecules inside the beaker

the extra energy that the molecules at the surface have relative to molecules inside the liquid

1.	If a glass tube is of insufficient length, water rises and overflows.
A.	True
B.	False
Answer» C.

2.	Consider a capillary tube in which water has risen. The contact angle is . The radius of the capillary tube is r . The surface tension is S . And the density of water is . What is the expression for the height of water risen in the tube? Assume the radius of meniscus to be R . Let the height of water risen in the tube be h .
A.	2Ssin / R g
B.	2S / R g
C.	2Scos / R g
D.	2S / r g
Answer» C. 2Scos / R g

3.	The contact angle determines whether liquid will rise or get depressed along a solid surface. Select the correct statement regarding the same.
A.	If contact angle is found to be less than 90 , the liquid will have raise along the solid surface
B.	If contact angle is found to be greater than 90 , then liquid will have depressed along the solid surface
C.	Liquid always rises along solid surface, irrespective of contact angle
D.	Liquid always gets depressed along solid surface, irrespective of contact angle
Answer» B. If contact angle is found to be greater than 90 , then liquid will have depressed along the solid surface

4.	A soap bubble contains two surface layers. What is the excess pressure just inside the first layer when seen from outside the bubble?
A.	2S/R
B.	4S/R
C.	-2S/R
D.	-4S/R
Answer» B. 4S/R

5.	What is the value of pressure inside the bubble of radius 1cm, if the bubble is in water at a depth (H) of 1m? Assume atmospheric pressure to be 1atm, surface tension = 0.075N/m & density of water = 1000kg/m³.
A.	110015 Pa
B.	109985 Pa
C.	26 atm
D.	4 atm
Answer» B. 109985 Pa

6.	Consider a spherical drop of liquid having radius R . Assume a diametric cross-section which divides the drop into two hemispheres. The hemispheres pull each other due to surface tension along the circumference of the diametrical cross-section. What is the value of this force?
A.	2 RS
B.	R<sup>2</sup> S
C.	2RS
D.	0
Answer» B. R<sup>2</sup> S

7.	What will be the change in surface energy when a drop of liquid (S = 0.08N/m) is divided into 10 equal droplets? Radius of initial single drop (R)= 5cm.
A.	0.1259 J
B.	0.1141 J
C.	0.2356 J
D.	0.1765 J
Answer» C. 0.2356 J

8.	The unit of surface tension is same as that of _________
A.	surface energy per unit volume
B.	force per unit area
C.	surface energy per unit area
D.	surface energy per unit length
Answer» D. surface energy per unit length

9.	Surface energy is ________________
A.	kinetic energy of the surface molecules
B.	the force per unit length acting on surface particles
C.	the energy of the molecules inside the beaker
D.	the extra energy that the molecules at the surface have relative to molecules inside the liquid
Answer» E.