A big drop of radius R is formed by 1000 small droplets of water, then the radius of small drop is

1. R/2                                     

2. R/5

3. R/6                                     

4. R/10

The surface tension of liquid is 0.5 N/m. If a film is held on a ring of area 0.02 ${\mathrm{m}}^2$, its surface energy is

1. $5\times {10}^{-2}<mspace\; width="1em"></mspace>\mathrm{joule}$                         
2. $2\times {10}^{-2}<mspace\; width="1em"></mspace>\mathrm{joule}$
3. $4\times {10}^{-4}<mspace\; width="1em"></mspace>\mathrm{joule}$                       
4. $0.8\times {10}^{-1}<mspace\; width="1em"></mspace>\mathrm{joule}$

If the surface tension of a liquid is T, the gain in surface energy for an increase in liquid surface by A is

1. ${\mathrm{AT}}^{-1}$                       

2. $\mathrm{AT}$

3. ${\mathrm{A}}^2\mathrm{T}$                         

4. ${\mathrm{A}}^2{\mathrm{T}}^2$

8000 identical water drops are combined to form a big drop. Then the ratio of the final surface energy to the initial surface energy of all the drops together is 
1. 1 : 10                     

2. 1 : 15

3. 1 : 20                     

4. 1 : 25

When two small bubbles join to form a bigger one, energy is

1. Released

2. Absorbed

3. Both (1) and (2)

4. None of these

The surface tension of a liquid at its boiling point

1. Becomes zero

2. Becomes infinity

3. is equal to the value at room temperature

4. is half to the value at the room temperature

A spherical drop of oil of radius 1 cm is broken into 1000 droplets of equal radii. If the surface tension of oil is 50 dynes/cm, the work done is 

1. 18 $\pi$ ergs                     

2. 180 $\pi$ ergs

3. 1800 $\pi$ ergs                 

4. 8000 $\pi$ ergs

A liquid drop of diameter D breaks upto into 27 small drops of equal size. If the surface tension of the liquid is $\mathrm{\sigma }$, then change in surface energy is 

(a) ${\mathrm{\pi D}}^2\mathrm{\sigma }$                          (b) $2{\mathrm{\pi D}}^2\mathrm{\sigma }$

(c) $3{\mathrm{\pi D}}^2\mathrm{\sigma }$                         (d) $4{\mathrm{\pi D}}^2\mathrm{\sigma }$

One thousand small water drops of equal radii combine to form a big drop. The ratio of final surface energy to the total initial surface energy is 

1. 1000 : 1               

2. 1 : 1000

3. 10 : 1                   

4. 1 : 10