A thin flat circular disc of radius \(4.5~\text {cm}\) is placed gently over the surface of water. If 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 |

From NCERT

NEET - 2024

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A wire of length \(L\) and radius \(r(r<<L)\) is kept floating on the surface of a liquid of density \(\rho\). The maximum radius of the wire for which it may not sink is (Surface tension of liquid is \(T\)):

1. \(\sqrt { \dfrac{T}{\rho g}}\)

2. \(\sqrt { \dfrac{2T}{\rho g}}\)

3. \(\sqrt{\dfrac{2T\rho}{\pi g}}\)

4. \(\sqrt{\dfrac{2T} {\pi \rho g}}\)

1. \(\sqrt { \dfrac{T}{\rho g}}\)

2. \(\sqrt { \dfrac{2T}{\rho g}}\)

3. \(\sqrt{\dfrac{2T\rho}{\pi g}}\)

4. \(\sqrt{\dfrac{2T} {\pi \rho g}}\)

Subtopic: Surface Tension |

52%

From NCERT

NEET - 2024

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The amount of energy required to form a soap bubble of radius \(2~\text{cm}\) from a soap solution is nearly:

\((\)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. \(3.01\times 10^{-4} ~\text{J}\)

\((\)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 |

58%

From NCERT

NEET - 2023

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If a soap bubble expands, the pressure inside the bubble:

1. is equal to the atmospheric pressure

2. decreases

3. increases

4. remains the same

1. is equal to the atmospheric pressure

2. decreases

3. increases

4. remains the same

Subtopic: Surface Tension |

68%

From NCERT

NEET - 2022

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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 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 |

61%

From NCERT

NEET - 2022

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A liquid does not wet the solid surface if the angle of contact is:

1. equal to $\mathrm{}$\(45^{\circ}\)

2. equal to \(60^{\circ}\)$\mathrm{}$

3. greater then \(90^{\circ}\)$\mathrm{}$

4. zero

Subtopic: Surface Tension |

77%

From NCERT

NEET - 2020

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A soap bubble, having a radius of \(1~\text{mm}\), is blown from a detergent solution having a surface tension of \(2.5\times 10^{-2}~\text{N/m}\)$$. The pressure inside the bubble equals at a point \(Z_0\) below the free surface of the water in a container. Taking \(g = 10~\text{m/s}^{2}\)${\mathrm{}}^{}$, the density of water \(= 10^{3}~\text{kg/m}^3\)${\mathrm{}}^{}$, the value of \(Z_0\) is:

1. \(0.5~\text{cm}\)

2. \(100~\text{cm}\)

3. \(10~\text{cm}\)

4. \(1~\text{cm}\)

Subtopic: Surface Tension |

55%

From NCERT

NEET - 2019

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A rectangular film of liquid is extended from \((4~\text{cm} \times 2~\text{cm})\) to \((5~\text{cm} \times 4~\text{cm}).\) If the work done is \(3\times 10^{-4}\) J, the value of the surface tension of the liquid is:

1. \(0.250\) Nm^{–1}

2. \(0.125\) Nm^{–1}

3. \(0.2\) Nm^{–1}

4. \(8.0\) Nm^{–1}

Subtopic: Surface Tension |

70%

From NCERT

NEET - 2016

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A certain number of spherical drops of a liquid of radius \({r}\) coalesce to form a single drop of radius \({R}\) and volume \({V}\). If \({T}\) is the surface tension of the liquid, then:

1. | energy \(= 4{VT}\left( \frac{1}{{r}} - \frac{1}{{R}}\right)\) is released. |

2. | energy \(={ 3{VT}\left( \frac{1}{{r}} + \frac{1}{{R}}\right)}\) is released. |

3. | energy \(={ 3{VT}\left( \frac{1}{{r}} - \frac{1}{{R}}\right)}\) is released. |

4. | energy is neither released nor absorbed. |

Subtopic: Surface Tension |

73%

From NCERT

AIPMT - 2014

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The wettability of a surface by a liquid depends primarily on:

1. | surface tension. |

2. | density. |

3. | angle of contact between the surface and the liquid. |

4. | viscosity. |

Subtopic: Surface Tension |

85%

From NCERT

AIPMT - 2013

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