question_answer 1)
A soap bubble assumes a spherical surface. Which of the following statement is wrong [NCERT 1976]
A)
The soap film consists of two surface layers of molecules back to back done
clear
B)
The bubble encloses air inside it done
clear
C)
The pressure of air inside the bubble is less than the atmospheric pressure; that is why the atmospheric pressure has compressed it equally from all sides to give it a spherical shape done
clear
D)
Because of the elastic property of the film, it will tend to shrink to as small a surface area as possible for the volume it has enclosed done
clear
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question_answer 2)
If two soap bubbles of different radii are in communication with each other [NCERT 1980; MP PMT/PET 1988; AIEEE 2004]
A)
Air flows from larger bubble into the smaller one done
clear
B)
The size of the bubbles remains the same done
clear
C)
Air flows from the smaller bubble into the large one and the larger bubble grows at the expense of the smaller one done
clear
D)
The air flows from the larger done
clear
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question_answer 3)
The surface tension of soap solution is \[25\times {{10}^{-3}}\,N{{m}^{-1}}\]. The excess pressure inside a soap bubble of diameter 1 cm is [AIIMS 1987]
A)
10 Pa done
clear
B)
20 Pa done
clear
C)
5 Pa done
clear
D)
None of the above done
clear
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question_answer 4)
When two soap bubbles of radius \[{{r}_{1}}\]and \[{{r}_{2}}\] \[({{r}_{2}}>{{r}_{1}})\] coalesce, the radius of curvature of common surface is [MP PMT 1996]
A)
\[{{r}_{2}}-{{r}_{1}}\] done
clear
B)
\[\frac{{{r}_{2}}-{{r}_{1}}}{{{r}_{1}}{{r}_{2}}}\] done
clear
C)
\[\frac{{{r}_{1}}{{r}_{2}}}{{{r}_{2}}-{{r}_{1}}}\] done
clear
D)
\[{{r}_{2}}+{{r}_{1}}\] done
clear
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question_answer 5)
The excess pressure due to surface tension in a spherical liquid drop of radius r is directly proportional to [MP PMT 1987; KCET 2000]
A)
\[r\] done
clear
B)
\[{{r}^{2}}\] done
clear
C)
\[{{r}^{-1}}\] done
clear
D)
\[{{r}^{-2}}\] done
clear
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question_answer 6)
A long cylindrical glass vessel has a small hole of radius 'r' at its bottom. The depth to which the vessel can be lowered vertically in the deep water bath (surface tension T) without any water entering inside is [MP PMT 1990]
A)
\[4T/\rho rg\] done
clear
B)
\[3T/\rho rg\] done
clear
C)
\[2T/\rho rg\] done
clear
D)
\[T/\rho rg\] done
clear
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question_answer 7)
If the surface tension of a soap solution is 0.03 MKS units, then the excess of pressure inside a soap bubble of diameter 6 mm over the atmospheric pressure will be
A)
Less than\[40N/{{m}^{2}}\] done
clear
B)
Greater than \[40N/{{m}^{2}}\] done
clear
C)
Less than\[20N/{{m}^{2}}\] done
clear
D)
Greater than \[20N/{{m}^{2}}\] done
clear
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question_answer 8)
The excess of pressure inside a soap bubble than that of the outer pressure is [MP PMT 1989; BHU 1995; MH CET 2002; RPET 2003; AMU (Engg.) 2000]
A)
\[\frac{2T}{r}\] done
clear
B)
\[\frac{4T}{r}\] done
clear
C)
\[\frac{T}{2r}\] done
clear
D)
\[\frac{T}{r}\] done
clear
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question_answer 9)
The pressure of air in a soap bubble of 0.7cm diameter is 8 mm of water above the pressure outside. The surface tension of the soap solution is [MP PET 1991; MP PMT 1997]
A)
\[100dyne/cm\] done
clear
B)
\[68.66dyne/cm\] done
clear
C)
\[137dyne/cm\] done
clear
D)
\[150dyne/cm\] done
clear
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question_answer 10)
Pressure inside two soap bubbles are 1.01 and 1.02 atmospheres. Ratio between their volumes is [MP PMT 1991]
A)
102 : 101 done
clear
B)
\[{{\left( 102 \right)}^{3}}:{{\left( 101 \right)}^{3}}\] done
clear
C)
8 : 1 done
clear
D)
2 : 1 done
clear
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question_answer 11)
A capillary tube of radius r is dipped in a liquid of density r and surface tension S. If the angle of contact is q, the pressure difference between the two surfaces in the beaker and the capillary
A)
\[\frac{S}{r}\cos \theta \] done
clear
B)
\[\frac{2S}{r}\cos \theta \] done
clear
C)
\[\frac{S}{r\cos \theta }\] done
clear
D)
\[\frac{2S}{r\cos \theta }\] done
clear
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question_answer 12)
The radii of two soap bubbles are r1 and r2. In isothermal conditions, two meet together in vaccum. Then the radius of the resultant bubble is given by [MP PMT 2001; RPET 1999; EAMCET 2003]
A)
\[R=({{r}_{1}}+{{r}_{2}})/2\] done
clear
B)
\[R={{r}_{1}}({{r}_{1}}{{r}_{2}}+{{r}_{2}})\] done
clear
C)
\[{{R}^{2}}=r_{1}^{2}+r_{2}^{2}\] done
clear
D)
\[R={{r}_{1}}+{{r}_{2}}\] done
clear
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question_answer 13)
The adjoining diagram shows three soap bubbles A, B and C prepared by blowing the capillary tube fitted with stop cocks, S1, S2 and S3. With stop cock S closed and stop cocks S1, S2 and S3 opened [CPMT 1988]
A)
B will start collapsing with volumes of A and C increasing done
clear
B)
C will start collapsing with volumes of A and B increasing done
clear
C)
C and A both will start collapsing with the volume of B increasing done
clear
D)
Volumes of A, B and C will become equal at equilibrium done
clear
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question_answer 14)
When a large bubble rises from the bottom of a lake to the surface, its radius doubles. If atmospheric pressure is equal to that of column of water height H, then the depth of lake is [AIIMS 1995; AFMC 1997]
A)
H done
clear
B)
2H done
clear
C)
7H done
clear
D)
8H done
clear
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question_answer 15)
A soap bubble in vacuum has a radius of 3 cm and another soap bubble in vacuum has a radius of 4 cm. If the two bubbles coalesce under isothermal condition, then the radius of the new bubble is [MP PMT/PET 1998; JIPMER 2000]
A)
2.3 cm done
clear
B)
4.5 cm done
clear
C)
5 cm done
clear
D)
7 cm done
clear
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question_answer 16)
The volume of an air bubble becomes three times as it rises from the bottom of a lake to its surface. Assuming atmospheric pressure to be 75 cm of Hg and the density of water to be 1/10 of the density of mercury, the depth of the lake is [AMU 1995]
A)
5 m done
clear
B)
10 m done
clear
C)
15 m done
clear
D)
20 m done
clear
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question_answer 17)
Excess pressure of one soap bubble is four times more than the other. Then the ratio of volume of first bubble to another one is [CPMT 1997; MH CET 2000]
A)
1 : 64 done
clear
B)
1 : 4 done
clear
C)
64 : 1 done
clear
D)
1 : 2 done
clear
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question_answer 18)
There are two liquid drops of different radii. The excess pressure inside over the outside is [JIPMER 1999]
A)
More in the big drop done
clear
B)
More in the small drop done
clear
C)
Equal in both drops done
clear
D)
There is no excess pressure inside the drops done
clear
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question_answer 19)
If pressure at half the depth of a lake is equal to 2/3 pressure at the bottom of the lake then what is the depth of the lake [RPET 2000]
A)
10m done
clear
B)
20m done
clear
C)
60m done
clear
D)
30m done
clear
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question_answer 20)
If the radius of a soap bubble is four times that of another, then the ratio of their pressures will be [AIIMS 2000]
A)
1 : 4 done
clear
B)
4 : 1 done
clear
C)
16 : 1 done
clear
D)
1 : 16 done
clear
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question_answer 21)
A spherical drop of water has radius 1 mm If surface tension of water is \[70\times {{10}^{-3}}\]N/m difference of pressures between inside and out side of the spherical drop is [CPMT 2000; AIIMS 2000]
A)
\[35\,N/{{m}^{-2}}\] done
clear
B)
\[70\,N/{{m}^{2}}\] done
clear
C)
\[140\,\,N/{{m}^{2}}\] done
clear
D)
Zero done
clear
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question_answer 22)
The pressure at the bottom of a tank containing a liquid does not depend on [Kerala (Engg.) 2001]
A)
Acceleration due to gravity done
clear
B)
Height of the liquid column done
clear
C)
Area of the bottom surface done
clear
D)
Nature of the liquid done
clear
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question_answer 23)
In capillary pressure below the curved surface of water will be [RPET 2001]
A)
Equal to atmospheric done
clear
B)
Equal to upper side pressure done
clear
C)
More than upper side pressure done
clear
D)
Lesser than upper side pressure done
clear
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question_answer 24)
Two soap bubbles of radii \[{{r}_{1}}\] and \[{{r}_{2}}\] equal to 4 cm and 5 cm are touching each other over a common surface \[{{S}_{1}}{{S}_{2}}\] (shown in figure). Its radius will be [MP PMT 2002]
A)
4 cm done
clear
B)
20 cm done
clear
C)
5 cm done
clear
D)
4.5 cm done
clear
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question_answer 25)
The pressure inside a small air bubble of radius 0.1 mm situated just below the surface of water will be equal to [Take surface tension of water \[70\times {{10}^{-3}}N{{m}^{-1}}\] and atmospheric pressure = \[1.013\times {{10}^{5}}N{{m}^{-2}}\]] [AMU (Med.) 2002]
A)
\[2.054\times {{10}^{3}}Pa\] done
clear
B)
\[1.027\times {{10}^{3}}Pa\] done
clear
C)
\[1.027\times {{10}^{5}}Pa\] done
clear
D)
\[2.054\times {{10}^{5}}Pa\] done
clear
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question_answer 26)
Two bubbles A and B \[(A>B)\] are joined through a narrow tube. Then [UPSEAT 2001; Kerala (Med.) 2002]
A)
The size of A will increase done
clear
B)
The size of B will increase done
clear
C)
The size of B will increase until the pressure equals done
clear
D)
None of these done
clear
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question_answer 27)
Two soap bubbles have different radii but their surface tension is the same. Mark the correct statement [MP PMT 2004]
A)
Internal pressure of the smaller bubble is higher than the internal pressure of the larger bubble done
clear
B)
Pressure of the larger bubble is higher than the smaller bubble done
clear
C)
Both bubbles have the same internal pressure done
clear
D)
None of the above done
clear
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question_answer 28)
If the excess pressure inside a soap bubble is balanced by oil column of height 2 mm, then the surface tension of soap solution will be (r = 1 cm and density d = 0.8 gm/cc) [J & K CET 2004]
A)
3.9 N/m done
clear
B)
\[3.9\text{ }\times {{10}^{2}}N/m\] done
clear
C)
\[3.9\text{ }\times {{10}^{3}}N/m\] done
clear
D)
3.9 dyne/m done
clear
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question_answer 29)
In Jager's method, at the time of bursting of the bubble [RPET 2002]
A)
The internal pressure of the bubble is always greater than external pressure done
clear
B)
The internal pressure of the bubble is always equal to external pressure done
clear
C)
The internal pressure of the bubble is always less than external pressure done
clear
D)
The internal pressure of the bubble is always slightly greater than external pressure done
clear
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question_answer 30)
The excess pressure in a soap bubble is thrice that in other one. Then the ratio of their volume is [RPMT 2003; CPMT 2001]
A)
1 : 3 done
clear
B)
1 : 9 done
clear
C)
27 : 1 done
clear
D)
1 : 27 done
clear
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