Vapour Pressure

Q.

A beaker containing a liquid is kept inside a big closed jar. If the air inside the jar is continuously pumped out, the pressure in the liquid near the bottom of the liquid will?

1. Decrease

2. Remain constant

3. first decreases and then increases

4. Increase

Q. A constant pressure air thermometer gave a reading of $47.5$ units of volume when immersed in ice cold water, and $67$ units in a boiling liquid. The boiling point of the liquid will be

1. ${112}^{\circ }C$
2. ${100}^{\circ }C$
3. ${135}^{\circ }C$
4. ${125}^{\circ }C$

Q.

A capillary tube of length 10 cm is dipped 3 cm inside water. The water rises up to 5 cm in the capillary. If the same tube is dipped 6 cm inside water, the water will rise in capillary up to the height

Q.

A capillary tube of radius 0.50 mm is dipped vertically in a pot of water. Find the difference between the pressure of the water in the tube 5.0 cm below the surface and the atmospheric pressure. Surface tension of water = 0.075 $N{m}^{-1}$.

Q.

Experiment to measure surface tension

Q. A horizontal pipe has a cross section of $10{\text{cm}}^2$ in one region and of $5{\text{cm}}^2$ in another. The water velocity at the first is $5{\text{ms}}^{–1}$ and the pressure in the second is $2\times {10}^5{\text{Nm}}^{–2}.$ Find the pressure of water in $1^{st}$ region (in ${10}^2\text{Pa}$).

1. $2000$
2. $1500$
3. $2375$
4. $1177.5$

Q. A vessel A has volume V and a vessel B has volume 2V. Both contain some water which has a constant volume. The pressure in the space above water is $p_a$ for vessel A and $p_b$ for vessel B.

1. $p_a=p_b$
2. $p_a=2p_b$
3. $p_b=2p_a$
4. $p_b=4p_a$

Q.

How does the density of a liquid change with the rise in its temperature ?

Q. A fluid is flowing through a horizontal pipe of varying cross - section, with speed $v\text{m}{s}^{-1}$ at a point where the pressure is $P\text{Pascal}$. At another point where pressure is $\frac{P}{2}\text{Pascal}$ its speed is $V{\text{ms}}^{-1}.$ If the density of fluid is $\rho {\text{kg/m}}^3$ and the flow is streamline, then $V$ is equal to :

1. $\sqrt{\frac{P}{\rho }+v}$
2. $\sqrt{\frac{2P}{\rho }+v^2}$
3. $\sqrt{\frac{P}{2\rho }+v^2}$
4. $\sqrt{\frac{P}{\rho }+v^2}$

Q.

What is meant by aqueous tension?

Q. The figure shows a model of perfume atomizer. When the bulb $\text{A}$ is compressed, air having density ${\rho }_a$ flows through the narrow tube. Consequently, pressure at the position of the vertical tube reduces. The liquid (perfume) of density $\rho$ rises through the vertical tube and emerges through the end. If the excess pressure applied to the bulb in this process be $\Delta p$, the minimum speed of air in the tube to lift the perfume is

1. $\sqrt{\frac{2(\Delta p+\rho gh)}{{\rho }_a}}$
2. $\sqrt{\frac{2(\Delta p-\rho gh)}{{\rho }_a}}$
3. $\sqrt{\frac{\Delta p+\rho gh}{{\rho }_a}}$
4. None of these

Q.

If the compressibility of water is σ per unit atmospheric pressure, then the decrease in volume V due to P atmospheric pressure will be

1. $\frac{\sigma P}{V}$

2. $\sigma PV$

3. $\frac{\sigma }{PV}$

4. $\frac{\sigma V}{P}$

Q. What is viscosity and coefficient of viscosity? Difference between them?

Q.

What do you understand by the following term?

Normal pressure

Q. A pressure cooker is based on the principle that the boiling point of water ............. (increases/decreases) with the increase in pressure.

Q. A thread is tied slightly loose to a wire frame as shown in the figure. The frame is dipped into a soap solution and then taken out so that, the frame is completely covered with the film. When the portion $A$ of the film is punctured with a pin, the thread will,

1. become convex towards $A$
2. become concave towards $A$
3. remain in the initial position
4. either $\left(A\right)$ or $\left(B\right)$, depending on size of A w.r.t. $B$
   

Q. The liquid drop of density ρ, radius r and surface tension (force per unit length ) σ oscillates with time period T. Which of the following expression for T² is correct
a.) ρr^3/σ
b.) ρσ/r³
c.)r³σ/ρ
d.) NONE

Q.

The condition of air in a closed room is described as follows. Temperature = ${25}^0$ C, relative humidity = 60 %, pressure = 104 kPa. If all the water vapour is removed from the room without changing the temperature, what will be the new pressure ? The saturation vapour pressure at ${25}^0$ C = 3.2 kPa.

Q. Surface of the lake is at $2^{\circ }C$. The temperature of the bottom of the lake is

1. $2^{\circ }C$
2. $3^{\circ }C$
3. $4^{\circ }C$
4. $1^{\circ }C$

Q. The velocity of efflux of a liquid through an orifice in the bottom of the tank does not depend upon:

1. size of orifice
2. height of liquid
3. acceleration due to gravity
4. density of liquid

Q.
Choose the correct option (s) for a liquid kept in closed vessel at constant temperature:

Q. The wettability of a surface by a liquid depends primarily on -

1. Angle of contact between the surface and the liquid
2. Viscosity
3. Surface tension
4. Density

Q. Two immiscible liquid of densities ${\rho }_1$ and ${\rho }_2$ are in equilibrium by forming a slant interface. The angle of inclination $\theta$ of the interface of the liquids is:

1. \N
2. ${\tan }^{-1}\frac{{\rho }_1+{\rho }_2}{{\rho }_1-{\rho }_2}$
3. ${\tan }^{-1}\frac{{\rho }_1}{{\rho }_2}$
4. ${\tan }^{-1}\frac{{\rho }_2}{{\rho }_1}$

Q. Assertion: Use of pressure cooker reduces cooking time.
Reason : At higher pressure cooking occurs faster.

1. If both assertion and reason are true, but the reason is not a correct explanation of the assertion.
2. If the assertion is true, but reason is false.
3. If both the assertion and reason are false.
4. If both assertion and reason are true and the reason is a correct explanation of the assertion.

Q. If pressure of $C{O}_2$ (real gas) in a container is given by P = $\frac{RT}{2V-b}-\frac{a}{4V^2}$ then mass of the gas in container is

1. 44 gm
2. 11 gm
3. 22 gm
4. 33 gm

Q. A brick weighing 4-0 kg is dropped into a 1 .0 m deep river from a height of 2 .0 m. Assuming that 80% of the gravitational potential energy is finally converted into thermal energy, find this thermal energy in calorie.

Q. Two liquids A and B are taken in two separate identical containers to the same height of the column then the pressure exerted by the two liquids in their respective containers is _______.

1. different if their densities are different
2. none of these
3. same if their densities are same.
4. different if their densities are same

Q.

Pure water vapour is trapped in a vessel of volume 10 $c{m}^3$. The relative humidity is 40 %. The vapour is compressed slowly and isothermally. Find the volume of the vapour at which it will start condensing.

Q. When piston is pulled in a spray pump, pressure inside the cylinder increases. Why liquid filled inside don't spill even after releasing the force on the piston?

1. Surface tension causes barrier force near the nozzle of the pump
2. Cross sectional area of nozzle is small and escape of liquid needs external force
3. Pressure inside cylinder is less than atmospheric pressure, hence liquid cant escape
4. Pressure inside cylinder is equal to atmospheric pressure, hence liquid cant escape

Q. Equation of an ellipse is given in its standard form as, $16x^2+y^2=16$. Length of the latus rectum is

1. $\frac{1}{2}$
2. $\frac{1}{4}$
3. $4$
4. $2$