# 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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Three liquids of densities $$\rho_1,\rho_2$$ and $$\rho_3$$ $$(\rho_1>\rho_2>\rho_3)$$ having the same value of surface tension $$T$$, rise to the same height in three identical capillaries. The angles of contact $\mathrm{}$$$\theta_1$$, $\mathrm{}$$$\theta_2$$, and $\mathrm{}$$$\theta_3$$ obey:
1. $$\frac{\pi}{2}>\theta_1>\theta_2>\theta_3 \geq 0$$
2. $$0 \leq \theta_1<\theta_2<\theta_3<\frac{\pi}{2}$$
3. $$\frac{\pi}{2}<\theta_1<\theta_2<\theta_3<\pi$$
4. $$\pi>\theta_1>\theta_2>\theta_3>\frac{\pi}{2}$$

Subtopic:  Capillary Rise |
68%
From NCERT
NEET - 2016
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A U-tube with both ends open to the atmosphere is partially filled with water. Oil, which is immiscible with water, is poured into one side until it stands at a level of $$10~\text{mm}$$ above the water level on the other side. Meanwhile, the water rises by $$65~\text{mm}$$ from its original level (see diagram). The density of the oil is:

1. $$425~\text{kg m}^{-3}$$
2. $$800~\text{kg m}^{-3}$$
3. $$928~\text{kg m}^{-3}$$
4. $$650~\text{kg m}^{-3}$$

Subtopic:  Pressure |
72%
From NCERT
NEET - 2017
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Two non-mixing liquids of densities $$\rho$$ and $$n\rho$$ $$(n>1)$$ are put in a container. The height of each liquid is $$h.$$ A solid cylinder of length $$L$$ and density $$d$$ is put in this container. The cylinder floats with its axis vertical and length $$rL~(r<1))$$ in the denser liquid. The density $$d$$ is equal to:
1. $$[2+(n+1)r ]\rho$$
2. $$[2+(n-1)r] \rho$$
3. $$[1+(n-1)r] \rho$$
4. $$[1+(n+1)r ]\rho$$

Subtopic:  Archimedes' Principle |
65%
From NCERT
NEET - 2016
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The cylindrical tube of a spray pump has a radius $$R,$$ one end of which has $$n$$ fine holes, each of radius $$r.$$ If the speed of the liquid in the tube is $$v,$$ the speed of the ejection of the liquid through the holes is:

 1 $$\frac{vR^{2}}{n^{2}r^{2}}$$ 2 $$\frac{vR^{2}}{nr^{2}}$$ 3 $$\frac{vR^{2}}{n^{3}r^{2}}$$ 4 $$\frac{v^{2}R}{nr}$$
Subtopic:  Equation of Continuity |
77%
From NCERT
NEET - 2015
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Water rises to height '$$h$$' in a capillary tube. If the length of capillary tube above the surface of the water is made less than $$'h'$$, then:

 1 water does not rise at all. 2 water rises up to the tip of capillary tube and then starts overflowing like a fountain. 3 water rises up to the top of capillary tube and stays there without overflowing. 4 water rises up to a point a little below the top and stays there.

Subtopic:  Capillary Rise |
71%
From NCERT
NEET - 2015
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The heart of a man pumps $$5~\text{L}$$ of blood through the arteries per minute at a pressure of $$150~\text{mm}$$ of mercury. If the density of mercury is $$13.6\times10^{3}~\text{kg/m}^{3}$$ $\mathrm{and}{}^{}$ $$g = 10~\text{m/s}^2$$, then the power of the heart in watt is:
1. $$1.70$$
2. $$2.35$$
3. $$3.0$$
4. $$1.50$$

Subtopic:  Pressure |
57%
From NCERT
NEET - 2015
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The approximate depth of an ocean is $$2700~\text{m}$$. The compressibility of water is $$45.4\times10^{-11}~\text{Pa}^{-1}$$ and the density of water is $$10^{3}~\text{kg/m}^3$$. What fractional compression of water will be obtained at the bottom of the ocean?
1. $$0.8\times 10^{-2}$$
2. $$1.0\times 10^{-2}$$
3. $$1.2\times 10^{-2}$$
4. $$1.4\times 10^{-2}$$

Subtopic:  Pressure |
69%
From NCERT
NEET - 2015
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A wind with a speed of $$40$$ m/s blows parallel to the roof of a house. The area of the roof is $$250$$ m2. Assuming that the pressure inside the house is atmospheric pressure, the force exerted by the wind on the roof and the direction of the force will be: ($$\rho_{\text {air }}=1.2$$)
1. $$4 \times 10^5$$ N, downwards
2. $$4 \times 10^5$$ N, upwards
3. $$2.4 \times 10^5$$ N, upwards
4. $$2.4 \times 10^5$$ N, downwards

Subtopic:  Bernoulli's Theorem |
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From NCERT
NEET - 2015
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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 |
72%
From NCERT
AIPMT - 2014
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