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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 101. |
If for a liquid in a vessle, force of a cohesion is twice of adhession :A. the meniscus will be convex upwardsB. the angle of contact will be obtusC. the liquid will descend in the capillary tubeD. the liquid will wet the solid |
| Answer» Correct Answer - A::B::C | |
| 102. |
Two capillaries A and B are dipped in water and held vertical . The diameter of A is twice that of B . The ratio of the heights to which water rises in A and B isA. `2 :1`B. `1:2`C. `4:1`D. `1:4` |
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Answer» Correct Answer - B `(h_(1))/(h_(2)) = (d_(2))/(d_(1)) = 1/2 ` |
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| 103. |
Two capillaries of small cross section are connected as shown in the figure. The right tube has cross sectional radius `R` and left one has a radius of `r (lt R)`. The tube of radius `R` is very long where as the tube of radius r is of short length. Water is slowly poured in the right tube. Contact angle for the tube wall and water is `theta = 0^(@)`. Let h be the height difference between water surface in the right and left tube. Surface tension of water is `T` and its density is `rho`. (a) Find the value of h if the water surface in the left tube is found to be flat. (b) Find the maximum value of h for which water will not flow out of the left tube . |
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Answer» Correct Answer - (a)`h=(2T)/(Rrhog)` (b) `(2T)/(rhog)((r+R)/(rR))` |
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| 104. |
When a capillary is dipped in water, water rises 0.015 m in it. If the surface tension of water is `75 xx 10^(-3) N//m` , the radius of capillary isA. `0.1 mm`B. `0.5 mm`C. `1mm`D. `2 mm` |
| Answer» Correct Answer - C | |
| 105. |
Calculate the energy released when 1000 small water drops each of same radius `10^(-7)m` coalesce to form one large drop. The surface tension of water is `7.0xx10^(-2)N//m`.A. `7 xx 10^(-12) J`B. `7.5 xx 10^(-12) J`C. `7.9 xx 10^(-12) J`D. `8.5 xx 10^(-12) J` |
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Answer» Correct Answer - C Let r be the radius of smaller drops and R of bigger one. Equating the initial and final volumes, we have `(4)/(3) piR^(3) = (1000) ((4)/(3) pi r^(3))` `rArr R = 10 r = (10) (10^(-7)) m rArr R = 10^(-6) m` Further, the water drops have only one free surface. Therefore, `Delta A = 4 piR^(2) - (1000) (4 pir^(2))` `= 4 pi [(10^(-6))^(2) - (10^(3)) (10^(-7))^(2)] = - 36 pi (1)^(-12) m^(2)` Here, negative sign implies that surface area is decreasing. Hence, energy released in the process, `U = S |DeltaA| = (7 xx 10^(-2)) (36 pi xx 10^(-12)) J` `= 7.9 xx 10^(-12) J` |
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| 106. |
What is ratio of surface energy of 1 small drop and 1 large drop, if 1000 small drops combined to form 1 large dropA. `100 :1`B. `1000 :1`C. `10 : 1`D. `1: 1000` |
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Answer» Correct Answer - D Volume of large drop `= 1000 xx` Volume of smaller droplets `(4)/(3) pi R^(3) = 1000 xx (4)/(3) pi r^(3) rArr R = 10 r` Surface energy of small drop, `E_(1) = S xx 4pi r^(2)` Surface energy of large drop, `E_(2) = S xx 4pi (10 r^(2))` `:. E_(1)//E_(2) = 1//100` |
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| 107. |
If two identical mercury drops are combined to form a single drop, then its temperature willA. DecreasesB. IncreasesC. Remains the sameD. None of the above |
| Answer» Correct Answer - B | |
| 108. |
The work done in blowing a soap bubble of radius r of the solution of surface tension T will beA. `8pir^(2)T`B. `2pir^(2)T`C. `4pir^(2)T`D. `4/3 pir^(2)T` |
| Answer» Correct Answer - A | |
| 109. |
The work done in blowing a soap bubble of radius 0.2 m is (the surface tension of soap solution being 0.06 N/m )A. `192 pi xx10^(-4) J`B. `280pixx10^(-4) j`C. `200 pixx10^(-3)` jD. None of these |
| Answer» Correct Answer - A | |
| 110. |
The work done in blowing a soap bubble of 10 cm radius is (Surface tension of the soap solution is `3/100` N/m)A. `75.36xx10^(-4) ` jouleB. `37.68xx10^(-4) ` jouleC. `150.72xx10^(-4)` jouleD. 75.36 joule |
| Answer» Correct Answer - A | |
| 111. |
What will be the work done in blowing a soap bubble of radius 2 cm , the surface tension of the soap solution is 20 dyne/cm at constant temperature ?A. `320 pi ` ergB. ` 640 pi ` ergC. `1240 pi ` ergD. `160 pi ` erg |
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Answer» Correct Answer - B `domega = 2T A` |
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| 112. |
A glass capillary tube sealed at the upper end has internal radius `r`. The tube is held vertical with its lower end touching the surface of water. Calculate the length `(L)` of such a tube for water in it to rise to a height `h (lt L)`. Atmospheric pressure is `P_(o)` and surface tension of water is T. Assume that water perfectly wets glass (Density of water = `rho`) |
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Answer» Correct Answer - `L=(P_(o)hr)/(2T-rhogrh)+h` |
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| 113. |
A capillary tube is radius 0.02 cm is dipped vertically in a beaker containing mercury . The level of mercury in the tube with respect to the mercury level in the beaker will be (Given density of mercury 13.5 g/cc ,Surface tension 540 dyne/cm and the angle of contact `135^(@)` )A. `2.88` cm belowB. `2.88 ` cm aboveC. ` 4.08 `cm belowD. ` 4.08 ` cm above |
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Answer» Correct Answer - A `2T cos theta = h rho gr` ` :. h = (2T cos theta )/(pgr) = (2xx540 xxcos_(1)xx35)/(13.5 xx1000xx0.02)` ` = (-2 xx540 xx sin 45)/(135xx2)` ` = (-540)/(135) xx1/(sqrt(2)) = -2.88 `cm below |
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| 114. |
A capillary tube of radius r is placed in a liquid I the angle of contact is `theta` , the radius of curvature R of the meniscus in the capillary isA. rB. `r sin theta`C. `r//cos theta`D. `r cos theta` |
| Answer» Correct Answer - C | |
| 115. |
A glass plate is partly dipped vertically in the mercury and the angle of contact is measured. If the plate is inclined, then the angle of contact willA. increasesB. decreasesC. remains unchangedD. first increases and then become constant |
| Answer» Correct Answer - C | |
| 116. |
A glass plate is partly dipped vertically in the mercury and the angle of contact is measured. If the plate is inclined, then the angle of contact willA. IncreasesB. Remain unchangedC. increases or decreasesD. Decreases |
| Answer» Correct Answer - B | |
| 117. |
Nature of meniscus for liquid having angle of contact as `0^@` isA. planeB. parabolicC. cylindricalD. hemispherical |
| Answer» Correct Answer - D | |
| 118. |
If the lower end of a capillary tube touches a liquid whose angle of contact is `90^@` , then the liquidA. rises in to tybeB. falls in the tubeC. may rise or fall in tubeD. neither rises nor falls inside the tube |
| Answer» Correct Answer - D | |
| 119. |
A vertical U tube has two limbs of unequal radii are 5 cm and 0.1 respectively . The tube is partly filled with mercury of density 13.6 `"g/cm"^(3)` and surface tension is 550 dyne /cm . Assume the two levels of the limbs isA. zeroB. `1.1` cmC. `1.61` cmD. `0.4` cm |
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Answer» Correct Answer - D `h_(2)-h_(1)=(2Tcostheta)/(rhog)(1/(r_(2))-1/r_(1))` ` = (2xx550 xx 1xx 4.9)/(13.6b xx 1800 xx 0.552)=0.4 ` cm |
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| 120. |
A liquid rises in a capillary tube when the angle of contact is:A. AcuteB. obtuseC. `90^(@)`D. zero |
| Answer» Correct Answer - A | |
| 121. |
When liquid does not rises in a capillary tube , the angle of contact is |
| Answer» Correct Answer - C | |
| 122. |
A liquid rises in a capillary tube when the angle of contact is:A. obtuseB. `180^(@)`C. acuteD. `90^(@)` |
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Answer» Correct Answer - C The angle of contact is acute (less than `90^(@)`). |
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| 123. |
When a capillary tube stands in water , water rises to a certain height in the tube . A similar experiment is done using another liquid and it is found that the liquid rises more than the water This difference might be due toA. the liquid has density greater than that of waterB. the tube used in the second experiment is larger boreC. the temperature of the liquid is higher than that of waterD. the surface tension of liquid is greater than that of water |
| Answer» Correct Answer - D | |
| 124. |
If the liquid rises in a capillary tube of radius 0.1 mm to a height of 6 cm . The angle of contact between the glass and turpentine is `17^(@)` and density of is 870 `kg//m^(3)` , g = 9.8 `m//s^(2)` . Then the surface tension of turpentine is , ( cos 17 = 0.9563)A. `0.026` N/mB. `2.6 ` N/mC. `0.26` N/mD. `2.6` dyne/cm |
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Answer» Correct Answer - A `T = (hrhogr)/(2costheta) = (6xx10^(-2)xx870xx9.8xx10^(-4))/(2 xx 0.9563) = 0.026` N/m |
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| 125. |
A 20 cm long capillary tube is dipped in water. The water rises up to 8 cm. If the entire arrangement is put in a freely falling elevator, the length of water column in the capillary tube will beA. 8 cmB. 10 cmC. 4 cmD. 20 cm |
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Answer» Correct Answer - D Water fills the tube entirely in gravity less condition i.e., 20 cm. |
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| 126. |
A `20cm` long capillary tube is dipped in water. The water rises upto `8 cm`. If the entire arrangment is put in a freely elevator, the length of water column in the capillary tube will be :A. `8 cm`B. `10 cm`C. `4 cm`D. `20 cm` |
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Answer» Correct Answer - D Water fills the tube entirely in gravity less condition. |
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| 127. |
Water rises to a height h in a capillary tube lowered vertically into water to a depth l as shown in the figure. The lower end of the tube is now closed, the tube is the taken out of the water and opend again. The length of the eater column remaining in the tube will be .A. `2h` if `l ge h` and `l + h` if `l le h`B. `h` if `l ge h` and `l + h` if `l le h`C. `4h` if `l ge h` and `l - h` if `l le h`D. `h//2` if `l ge h` and `l + h` if `l le h` |
| Answer» Correct Answer - A | |
| 128. |
A capillary tube is ipped in water . It rises to height of 4 cm above the surroundings liquid . If the angle of caontact is zero and radius of tube is 0.4 mm , then the surface tension of liquid will beA. `78.4` dyne/cmB. `7.84` dyne / cmC. 784 dyne/cmD. 72 dyne/cm |
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Answer» Correct Answer - A ` 2T cos theta = h rho gr` |
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| 129. |
In a capillary tube experiment, a vertical 30 cm long capillary tube is dipped in water. The water rises up to a height of 10 cm due to capillary action. If this experiment is conducted in a freely falling elevator, the length of te water column becomesA. `10 cm`B. `20 cm`C. `30 cm`D. Zero |
| Answer» Correct Answer - C | |
| 130. |
Water rises upto 10 cm height in a long capillary tube. If this tube is immersed in water so that the height above the water surface is only 8 cm, thenA. Water flows out continously from the upper andB. Water rises upto end and forms a spherical surfaceC. Water only rises upto 6 c m heightD. Water does not rise at all |
| Answer» Correct Answer - B | |
| 131. |
A narrow capillary tube when dipped in beaker containing water, the rise is 20 cm . If the area of cross section of the bore is reduced to `(1//4)^(th)` calue , water will rise to a height ofA. 10 cmB. 20 cmC. 40 cmD. 80 cm |
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Answer» Correct Answer - C ` A_(2)= 1/4 A_(1)` `pir_(2)^(2)=1/4pir_(1)^(2)` `r_(2)=1/2r_(1)` `h_(2)=(h_(1)r_(1))/(r_(2)) =(h_(1)r_(1))/(1/2r_(2))=2h_(1)=2xx20` =40 cm |
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| 132. |
Water rises to a height of 10 cm in capillary tube and mercury falls to a depth of 3.112 cm in the same capillary tube. If the density of mercury is 13.6 and the angle of contact for mercury is `135^(@)`, the ratio of surface tension of water and mercury isA. `1:0.15`B. `1:3`C. `1:6`D. `1.5 : 1` |
| Answer» Correct Answer - C | |
| 133. |
If a capillary tube of diameter 0.4 m is dipped vertically into water, then the height to which water rises in the capillary tube will be ,A. `7.143` cmB. `0 . 013` cmC. `714 .3` cmD. 7143 cm s |
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Answer» Correct Answer - A ` h = (2T cos theta )/(rho gr) = (2xx 7xx 10^(-2)xx1)/(10^(3)xx9.8 xx2xx10^(-4))=7.143` cm |
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| 134. |
Two capillary tubes of radius 0.5 mm and 1 mm when dipped in a liquid of surface tension 49 dyne / cm vertically , it is observed that the liquid level difference is found to be 1.25 cm in the tubes . Then the density of the liquid will be `(theta = 0^(@))`A. `0.08` g/ccB. `0.8` g/ccC. `0.04`g/ccD. `0.4`g/c |
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Answer» Correct Answer - B `h_(1)-h_(2) = (2tcos theta )/(rho g )[ 1/(r_(1))-1/(r_(2))]` ` rho = (2T cos theta )/(g(h_(1)-h_(2)))[1/r_(1)-1/(r_(2))]` `= (2xx 49 xx cos (0))/(980 xx 1.25 )[1/(0.05)-1/(0.1)]` ` = 1/ 10 xx 4/5 xx (20 - 10 ) = ( 4xx 10)/50 ` = 0.8 g/cc . |
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| 135. |
Water rises to a height of 16.3 cm in a capillary of height 18 cm above the water leve. If the tube is cut at a height of 12 cm -A. water will come as a fountain from the capillary tubeB. water will stay at a height of 12 cm in the capillary tubeC. the height of water in the capillary tube will be 10.3 cmD. water will flow down the sides of the capillary tube |
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Answer» Correct Answer - B The product h r = const . Therefore the radius of curvature of meniscus is adjusted . |
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| 136. |
A capillary tube of uniform bore is dipped vertically in water which rises by 7 cm in tube . Then the radius of capillary tube is (S.T of water is 70 dyne/cm , g = 1000 `"cm/s"^(2) theta = 0^(@)) `A. `0.2 ` mmB. 2 mmC. `0.2` cmD. 2 cm |
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Answer» Correct Answer - A ` r = (2Tcos theta )/(h rho g) = (2xx70xx1)/(7xx10^(3)xx1) = 0.2 ` mm |
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| 137. |
Water rises to a height of 16.3 cm in a capillary of height 18 cm above the water leve. If the tube is cut at a height of 12 cm -A. Water will come as a fountain from the capillary tubeB. Water will stay at a height of 12 cm in the capillary tubeC. The height of the water in the capillary will be 10.3 cmD. Water will flow down the sides of the capillary tube |
| Answer» Correct Answer - B | |
| 138. |
When a capillary tube of radius `r` is dipped vertically in a liquid of surface tension T, the liquid rises to a height `h` in the tube above the level outside the tube . If the angle of contact is `theta` the density of the liquid is `rho` then the pressure difference between the points A and B is A. ` 2T r cos theta`B. `(2Tcos theta)/r`C. `T r cos theta`D. `(Tcos theta )/r` |
| Answer» Correct Answer - B | |
| 139. |
If liquid level falls in a capillary then radius of capillary willA. IncreasesB. DecreasesC. UnchangedD. None of these |
| Answer» Correct Answer - A | |
| 140. |
Water rises to a height `h` in a capillary at the surface of earth. On the surface of the moon the height of water column in the same capillary will be-A. `6h`B. `(1)/(6)h`C. hD. Zero |
| Answer» Correct Answer - A | |
| 141. |
In Acca lamp , oil rises through the wick , due toA. viscosityB. rigidityC. capillarityD. surface tension |
| Answer» Correct Answer - C | |
| 142. |
There is a soap bubble of radius `2.4 xx 10^(-4)m` in air cylinder at a pressure of `10^(5) N//m^(2)`. The air in the cylinder is compressed isothermal until the radius of the bubble is halved. Calculate the new pressure of air in the cylinder. Surface tension of soap solution is `0.08 Nm^(-1)`. |
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Answer» Similar to question no. `37`, `p_(2) = 8p_(1) + (245)/(c) = 8 xx 10^(5) + (24 xx .08)/(2.4 xx 10^(-4))` `= 8.08 xx 10^(5) N//m^(2)` |
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| 143. |
The correct curve between the height or depression `h` of liquid in a capillary tube and its radius isA. B. C. D. |
| Answer» Correct Answer - B | |
| 144. |
Calculate the work done in spraying a spherical drop of mercury of 1 mm radius into a million droplets of equal size. The surface tension of mercury `=550 xx10^(-3) Nm^(-1)` |
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Answer» Correct Answer - `6.844xx10^(-4)`J |
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| 145. |
The exess pressure inside a drop of soap solution is Pd and that inside a soap bubble of same radius is` P_(d)` thenA. `P_(d)=P_(b)`B. `P_(b)=2P_(d)`C. `P_(d)=2P_(b)`D. `P_(b)=4P_(d)` |
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Answer» Correct Answer - B ` P_(d) = (2T)/r` `P_(b) = (4T)/r ` ` (P_(b))/(P_(d))= (4T)/r xx r/(2T) = 2 ` ` P_(b)=2P_(d)` |
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| 146. |
Surface tension is due toA. Frictional force between moleculesB. Cohesive forces between moleculesC. Adhesive force between moleculesD. Gravitational forces |
| Answer» Correct Answer - B | |
| 147. |
The rain are in spherical shape due toA. surface tension of water is greater than the weightB. capillaryC. downward motionD. acceleration due to gravity |
| Answer» Correct Answer - A | |
| 148. |
The rain are in spherical shape due toA. Density of the liquidB. surface tensionC. Atmospheric pressureD. Gravity |
| Answer» Correct Answer - B | |
| 149. |
At critical temperature, the surface tension of a liquidA. ZeroB. infiniteC. Between 0 and `oo`D. Can not be determined |
| Answer» Correct Answer - A | |
| 150. |
At critical temperature, the surface tension of a liquidA. zeroB. oneC. infinityD. any finite values |
| Answer» Correct Answer - A | |