Q. No.For a surface molecule,
| (a) | The net force on it is zero. |
| (b) | There is a net downward force. |
| (c) | The potential energy is less than that of a molecule inside. |
| (d) | The potential energy is more than that of a molecule inside. |
Choose the correct alterative/s:
| 1. | (b), (c) | 2. | (b), (d) |
| 3. | (c), (d) | 4. | (a), (d) |
Subtopic: Surface Tension |
64%
Level 2: 60%+
Hints
The amount of energy required to form a soap bubble of radius \(2~\text{cm}\) from a soap solution is nearly:
\((\)the surface tension of soap solution \(0.03~\text{Nm}^{-1})\)
1. \(50.1 \times 10^{-4}~\text{J}\)
2. \(30.16 \times 10^{-4}~ \text{J}\)
3. \(5.06 \times 10^{-4} ~\text{J}\)
4. \(3.01\times 10^{-4} ~\text{J}\)
\((\)the surface tension of soap solution \(0.03~\text{Nm}^{-1})\)
1. \(50.1 \times 10^{-4}~\text{J}\)
2. \(30.16 \times 10^{-4}~ \text{J}\)
3. \(5.06 \times 10^{-4} ~\text{J}\)
4. \(3.01\times 10^{-4} ~\text{J}\)
Subtopic: Surface Tension |
63%
Level 2: 60%+
NEET - 2023
Hints
A thin flat circular disc of radius \(4.5~\text {cm}\) is placed gently over the surface of water. If the surface tension of water is \(0.07~\text{Nm}^{-1},\) then the excess force required to take it away from the surface is:
1. \(198~\text{N}\)
2. \(1.98~\text{mN}\)
3. \(99~\text{N}\)
4. \(19.8~\text{mN}\)
1. \(198~\text{N}\)
2. \(1.98~\text{mN}\)
3. \(99~\text{N}\)
4. \(19.8~\text{mN}\)
Subtopic: Surface Tension |
53%
Level 3: 35%-60%
NEET - 2024
Hints
A liquid drop of radius \(R\) split into \(27\) small drops of equal radius. If the surface tension of the liquid is \(T,\) then change in surface energy is:
| 1. | \(4\pi R^2T\) | 2. | \(8\pi R^2T\) |
| 3. | \(16\pi R^2T\) | 4. | \(27\pi R^2T\) |
Subtopic: Surface Tension |
75%
Level 2: 60%+
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Hints
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What will be the work done against surface tension in blowing a soap bubble from a radius of \(20\) cm to \(40\) cm, if the surface tension of soap solution is \(25\times10^{-3}\) N m–1?
1. \(37.5\) mJ
2. \(75\) mJ
3. \(50\) mJ
4. \(150\) mJ
1. \(37.5\) mJ
2. \(75\) mJ
3. \(50\) mJ
4. \(150\) mJ
Subtopic: Surface Tension |
62%
Level 2: 60%+
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The radius of a soap bubble is \(R.\) The surface tension of the soap solution is \(T,\) if the radius of the soap bubble is increased to \(3R\) then the energy required is:
(consider no loss anywhere)
1. \(64\pi R^{2}T\)
2. \(9\pi R^{2}T\)
3. \(32\pi R^{2}T\)
4. \(72\pi R^{2}T\)
(consider no loss anywhere)
1. \(64\pi R^{2}T\)
2. \(9\pi R^{2}T\)
3. \(32\pi R^{2}T\)
4. \(72\pi R^{2}T\)
Subtopic: Surface Tension |
65%
Level 2: 60%+
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Choose the incorrect statement:
| 1. | Soap bubbles have two air-liquid interfaces. |
| 2. | Liquid drops have one air-liquid interface. |
| 3. | Air cavity inside a liquid has one air-liquid interface. |
| 4. | Air cavity inside a liquid has two air-liquid interfaces. |
Subtopic: Surface Tension |
74%
Level 2: 60%+
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Given below are two statements:
| Assertion (A): | Smaller drops of water resist deformation forces better than larger drops. |
| Reason (R): | Excess pressure inside the drop is inversely proportional to its radius. |
| 1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
| 2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
| 3. | (A) is True but (R) is False. |
| 4. | (A) is False but (R) is True. |
Subtopic: Surface Tension |
80%
Level 1: 80%+
Hints
A big drop is divided into \(1000\) identical droplets. If the big drop had surface energy \(U_{i}\) and all small droplets together had a surface energy \(U_{f},\) then \(\dfrac {U_i}{U_f}\) is equal to:
1. \(1/100\)
2. \(10\)
3. \(1/10\)
4. \(1000\)
1. \(1/100\)
2. \(10\)
3. \(1/10\)
4. \(1000\)
Subtopic: Surface Tension |
65%
Level 2: 60%+
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Air is pushed carefully into a soap bubble of radius \(r\) to double its radius. If the surface tension of the soap solution is \(T,\) then the work done in the process is:
| 1. | \(12\pi r^2T\) | 2. | \(24\pi r^2T \) |
| 3. | \(4\pi r^2T\) | 4. | \(8\pi r^2T\) |
Subtopic: Surface Tension |
63%
Level 2: 60%+
NEET - 2022
Hints
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