# Practice Test

Q1) Estimate the pressure difference between the lower and upper surfaces of the wings. Show Answer

Q2) What is the pressure difference between the two ends of the tube? Show Answer

Q3) What is the Reynolds number? Show Answer

Q4) The equation of continuity. Which is valid for incompressible fluids is a statement of Show Answer

Q5) The Bernoulli's equation that is valid for nor-viscous, incompressible fluids having laminar flow is a consequence of Show Answer

Q6) Magnus effect is the Show Answer

Q7) The dimensions of viscosity are Show Answer

Q8) The Reynold's number equals Show Answer

Q9) The surface energy of a liquid drop of radius r is proportional to Show Answer

Q10) In a satellite moving around any planet, the gravitational force is effectively balanced. If the ice cube exists there, and it melts with passage of time, its shape will Show Answer

Q11) A liquid is contained in a vessel. The liquid solid adhesive force is very weak as compared to the cohesive force in the liquid. The shape of the liquid surface will be Show Answer

Q12) Two liquids drops coalesce to form a large drop. Now, Show Answer

Q13) Statement 1 : The viscosity of a liquid increases with rise of temperature.
Statement 2: Viscosity of liquid is the property of the liquid by virtue of which it opposes the relative motion amongst its different layers. Show Answer

Q14) Statement 1 : Two row boats moving parallel to each other and nearby, are attracted towards each other.
Statement 2 : Increase of velocity of fluid flow decreases the pressure between them. Show Answer

Q15) The correct diagram showing the trajectories is Show Answer

Q16) The term 'surface of a liquid' means Show Answer

Q17) If ice melts under gravity free conditions in vacuum, the final geometrical shape will be Show Answer

Q18) The excess pressure due to surface tension inside a spherical drop in 6 units. If eight such drops combine, then the excess pressure due to surface tension inside the larger drop is Show Answer

Q19) What is the ratio of excess pressures inside two soap bubbles of diameters in the ratio 2 : 1? Show Answer

Q20) The surface energy of a liquid drop is E. It is sprayed into 1000 equal droplets. Then its surface energy becomes Show Answer

Q21) The pressure energy per unit volume of a liquid is Show Answer

Q22) A water tank of height 10 m, completely filled with water is placed on a level ground. It has two holes one at 3 m and the other at 7 m from its base. The water ejecting from Show Answer

Q23) The vertical sections of the wing of a fan are shown in figure. Maximum upthrust is in Show Answer

Q24) The work done by the force of gravity per unit volume is Show Answer

Q25) Statement 1 : When two soap bubbles having different radii are kept in contact, the common surface at their interface bulges into the larger bubble.
Statement 2: Pressure inside the smaller bubble is larger. Show Answer

Q26) Statement 1 : All the rain drops do not reach the surface of the earth with the same velocity.
Statement 2 : An object falling through a viscous medium eventually attains a terminal velocity. Show Answer

Q27) What is the work done by surface tension force? Show Answer

Q28) What is the rise in the potential energy of the liquid? Show Answer

Q29) What is the work done against friction of the capillary. (Assume liquid rises slowly in the tube) Show Answer

Q30) The value of surface tension of a liquid at critical temperature is Show Answer

Q31) The spherical shape of rain-drop is due to Show Answer

Q32) Surface tension is due to Show Answer

Q33) When there is no external force, the shape of a liquid drop is determined by Show Answer

Q34) Soap helps in cleaning clothes, because Show Answer

Q35) A pin or a needle floats on the surface of water, the reason for this is Show Answer

Q36) Coatings used on raincoat are waterproof because Show Answer

Q37) If temperature increases, the surface tension of a liquid Show Answer

Q38) A drop of oil is placed on the surface of water. Which of the following statement is correct Show Answer

Q39) The temperature at which the surface tension of water is zero Show Answer

Q40) A small air bubble is at the inner surface of the bottom of a beaker filled with cold water. Now water of the beaker is heated. The size of bubble increases. The reason for this may be Show Answer

Q41) The spiders and insects move and run about on the surface of water without sinking because Show Answer

Q42) Small droplets of a liquid are usually more spherical in shape than larger drops of the same liquid because Show Answer

Q43) Hairs of shaving brush cling together when it is removed from water due to Show Answer

Q44) A square frame of side L is dipped in a liquid. On taking out, a membrane is formed. If the surface tension of the liquid is T, the force acting on the frame will be Show Answer

Q45) Water does not wet an oily glass because Show Answer

Q46) A water drop takes the shape of a sphere in a oil while the oil drop spreads in water, because

Q47) Which of the fact is not due to surface tension Show Answer

Q48) In the glass capillary tube, the shape of the surface of the liquid depends upon Show Answer

Q49) Force necessary to pull a circular plate of 5 cm radius from water surface for which surface tension is 75 dynes/cm, is Show Answer

Q50) The property of surface tension is obtained in Show Answer

Q51) The surface tension of a liquid Show Answer

Q52) If two glass plates are quite nearer to each other in water, then there will be force of Show Answer

Q53) On mixing the salt in water, the surface tension of water will Show Answer

Q54) Consider a liquid contained in a vessel. The liquid solid adhesive force is very weak as compared to the cohesive force in the liquid. The shape of the liquid surface near the solid shall be Show Answer

Q55) At which of the following temperatures, the value of surface tension of water is minimum Show Answer

Q56) If a glass rod is dipped in mercury and withdrawn out, the mercury does not wet the rod because Show Answer

Q57) Mercury does not wet glass, wood or iron because Show Answer

Q58) Surface tension of a liquid is found to be influenced by Show Answer

Q59) When a drop of water is dropped on oil surface, then Show Answer

Q60) Two pieces of glass plate one upon the other with a little water in between them cannot be separated easily because of Show Answer

Q61) Small liquid drops assume spherical shape because Show Answer

Q62) It is easy to wash clothes in hot water because its Show Answer

Q63) Due to which property of water, tiny particles of camphor dance on the surface of water Show Answer

Q64) Oil spreads over the surface of water whereas water does not spread over the surface of the oil, due to Show Answer

Q65) Cohesive force is experienced between Show Answer

Q66) The property utilized in the manufacture of lead shots is Show Answer

Q67) The dimensions of surface tension are Show Answer

Q68) A wooden stick 2m long is floating on the surface of water. The surface tension of water 0.07 N/m. By putting soap solution on one side of the sticks the surface tension is reduced to 0.06 N/m. The net force on the stick will be Show Answer

Q69) The force required to take away a flat circular plate of radius 2 cm from the surface of water, will be (the surface tension of water is 70 dyne/cm) Show Answer

Q70) Surface tension may be defined as Show Answer

Q71) Energy needed in breaking a drop of radius R into n drops of radii r is given by Show Answer

Q72) The potential energy of a molecule on the surface of liquid compared to one inside the liquid is Show Answer

Q73) Two droplets merge with each other and forms a large droplet. In this process Show Answer

Q74) A drop of liquid of diameter 2.8 mm breaks up into 125 identical drops. The change in energy is nearly (S.T. of liquid =75 dynes/cm) Show Answer

Q75) Radius of a soap bubble is 'r', surface tension of soap solution is T. Then without increasing the temperature, how much energy will be needed to double its radius Show Answer

Q76) A spherical liquid drop of radius R is divided into eight equal droplets. If surface tension is T, then the work done in this process will be Show Answer

Q77) The amount of work done in blowing a soap bubble such that its diameter increases from d to D is (T= surface tension of the solution) Show Answer

Q78) If T is the surface tension of soap solution, the amount of work done in blowing a soap bubble from a diameter D to 2D is Show Answer

Q79) If work W is done in blowing a bubble of radius R from a soap solution, then the work done in blowing a bubble of radius 2R from the same solution is Show Answer

Q80) A spherical drop of oil of radius 1 cm is broken into 1000 droplets of equal radii. If the surface tension of oil is 50 dynes/cm, the work done is Show Answer

Q81) The work done in blowing a soap bubble of radius r of the solution of surface tension T will be Show Answer

Q82) If two identical mercury drops are combined to form a single drop, then its temperature will Show Answer

Q83) If the surface tension of a liquid is T, the gain in surface energy for an increase in liquid surface by A is Show Answer

Q84) The surface tension of a liquid at its boiling point Show Answer

Q85) What is ratio of surface energy of 1 small drop and 1 large drop, if 1000 small drops combined to form 1 large drop Show Answer

Q86) One thousand small water drops of equal radii combine to form a big drop. The ratio of final surface energy to the total initial surface energy is Show Answer

Q87) A big drop of radius R is formed by 1000 small droplets of water, then the radius of small drop is Show Answer

Q88) Which of the following statements are true in case when two water drops coalesce and make a bigger drop Show Answer

Q89) 8000 identical water drops are combined to form a big drop. Then the ratio of the final surface energy to the initial surface energy of all the drops together is Show Answer

Q90) 8 mercury drops coalesce to form one mercury drop, the energy changes by a factor of Show Answer

Q91) When two small bubbles join to form a bigger one, energy is Show Answer

Q92) Two small drops of mercury, each of radius R, coalesce to form a single large drop. The ratio of the total surface energies before and after the change is Show Answer

Q93) Radius of a soap bubble is increased from R to 2R work done in this process in terms of surface tension is Show Answer

Q94) 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) Show Answer

Q95) If two soap bubbles of equal radii r coalesce then the radius of curvature of interface between two bubbles will be Show Answer

Q96) A liquid does not wet the sides of a solid, if the angle of contact is Show Answer

Q97) The meniscus of mercury in the capillary tube is Show Answer

Q98) When the temperature is increased the angle of contact of a liquid Show Answer

Q99) The angle of contact between glass and mercury is Show Answer

Q100) A mercury drop does not spread on a glass plate because the angle of contact between glass and mercury is Show Answer

Q101) A liquid is coming out from a vertical tube. The relation between the weight of the drop W, surface tension of the liquid T and radius of the tube r is given by, if the angle of contact is zero Show Answer

Q102) The parts of motor cars are polished by chromium because the angle of contact between water and chromium is Show Answer

Q103) 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 will Show Answer

Q104) The liquid meniscus in capillary tube will be convex, if the angle of contact is Show Answer

Q105) If a water drop is kept between two glass plates, then its shape is Show Answer

Q106) The value of contact angle for kerosene with solid surface. Show Answer

Q107) A liquid wets a solid completely. The meniscus of the liquid in a sufficiently long tube is Show Answer

Q108) What is the shape when a non-wetting liquid is placed in a capillary tube Show Answer

Q109) For which of the two pairs, the angle of contact is same Show Answer

Q110) If the surface of a liquid is plane, then the angle of contact of the liquid with the walls of container is Show Answer

Q111) A soap bubble assumes a spherical surface. Which of the following statement is wrong Show Answer

Q112) If two soap bubbles of different radii are in communication with each other Show Answer

Q113) The excess pressure due to surface tension in a spherical liquid drop of radius r is directly proportional to Show Answer

Q114) A long cylindrical glass vessel has a small hole of radius 'r' at its bottom. The depth to which the vessel can be lowered vertically in the deep water bath (surface tension T) without any water entering inside is Show Answer

Q115) If the surface tension of a soap solution is 0.03 MKS units, then the excess of pressure inside a soap bubble of diameter 6 mm over the atmospheric pressure will be Show Answer

Q116) The excess of pressure inside a soap bubble than that of the outer pressure is Show Answer

Q117) The pressure of air in a soap bubble of 0.7cm diameter is 8 mm of water above the pressure outside. The surface tension of the soap solution is Show Answer

Q118) Pressure inside two soap bubbles are 1.01 and 1.02 atmospheres. Ratio between their volumes is Show Answer

Q119) When a large bubble rises from the bottom of a lake to the surface, its radius doubles. If atmospheric pressure is equal to that of column of water height H, then the depth of lake is Show Answer

Q120) A soap bubble in vacuum has a radius of 3 cm and another soap bubble in vacuum has a radius of 4 cm. If the two bubbles coalesce under isothermal condition, then the radius of the new bubble is Show Answer

Q121) The volume of an air bubble becomes three times as it rises from the bottom of a lake to its surface. Assuming atmospheric pressure to be 75 cm of Hg and the density of water to be 1/10 of the density of mercury, the depth of the lake is Show Answer

Q122) Excess pressure of one soap bubble is four times more than the other. Then the ratio of volume of first bubble to another one is Show Answer

Q123) There are two liquid drops of different radii. The excess pressure inside over the outside is Show Answer

Q124) If pressure at half the depth of a lake is equal to 2/3 pressure at the bottom of the lake then what is the depth of the lake Show Answer

Q125) If the radius of a soap bubble is four times that of another, then the ratio of their pressures will be Show Answer

Q126) The pressure at the bottom of a tank containing a liquid does not depend on Show Answer

Q127) In capillary pressure below the curved surface of water will be Show Answer

Q128) Two bubbles A and B are (A > B) joined through a narrow tube. Then Show Answer

Q129) Two soap bubbles have different radii but their surface tension is the same. Mark the correct statement Show Answer

Q130) If the excess pressure inside a soap bubble is balanced by oil column of height 2 mm, then the surface tension of soap solution will be (r = 1 cm and density d = 0.8 gm/cc) Show Answer

Q131) In Jager's method, at the time of bursting of the bubble Show Answer

Q132) The excess pressure in a soap bubble is thrice that in other one. Then the ratio of their volume is Show Answer

Q133) When two capillary tubes of different diameters are dipped vertically, the rise of the liquid is Show Answer

Q134) Due to capillary action, a liquid will rise in a tube, if the angle of contact is Show Answer

Q135) In the state of weightlessness, a capillary tube is dipped in water, then water Show Answer

Q136) Two parallel glass plates are dipped partly in the liquid of density 'd' keeping them vertical. If the distance between the plates is 'x', surface tension for liquids is T and angle of contact is , then rise of liquid between the plates due to capillary will be Show Answer

Q137) It is not possible to write directly on blotting paper or newspaper with ink pen Show Answer

Q138) Two capillary tubes P and Q are dipped in water. The height of water level in capillary P is 2/3 to the height in Q capillary. The ratio of their diameters Show Answer

Q139) Two capillaries made of same material but of different radii are dipped in a liquid. The rise of liquid in one capillary is 2.2 cm and that in the other is 6.6 cm. The ratio of their radii is Show Answer

Q140) When a capillary is dipped in water, the water rises to a height h. If the length of the capillary is made less than h, then Show Answer

Q141) 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, then Show Answer

Q142) A capillary tube made of glass is dipped into mercury. Then Show Answer

Q143) By inserting a capillary tube upto a depth l in water, the water rises to a height h. If the lower end of the capillary is closed inside water and the capillary is taken out and closed end opened, to what height the water will remain in the tube Show Answer

Q144) If the diameter of a capillary tube is doubled, then the height of the liquid that will rise is Show Answer

Q145) Two capillary tubes of radii 0.2 cm and 0.4 cm are dipped in the same liquid. The ratio of heights through which liquid will rise in the tubes is Show Answer

Q146) The action of a nib split at the top is explained by Show Answer

Q147) The correct relation is Show Answer

Q148) Water rises upto a height h in a capillary on the surface of earth in stationary condition. Value of h increases if this tube is taken Show Answer

Q149) During capillary rise of a liquid in a capillary tube, the surface of contact that remains constant is of Show Answer

Q150) A shell having a hole of radius r is dipped in water. It holds the water upto a depth of h then the value of r is Show Answer

Q151) In a capillary tube, water rises by 1.2 mm. The height of water that will rise in another capillary tube having half the radius of the first, is Show Answer

Q152) If capillary experiment is performed in vacuum then for a liquid there Show Answer

Q153) If liquid level falls in a capillary then radius of capillary will Show Answer

Q154) 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 Show Answer

Q155) The surface tension for pure water in a capillary tube experiment is Show Answer

Q156) In a capillary tube experiment, a vertical 30 cm long capillary tube is dipped in water. The water rises up to a height of 10cm due to capillary action. If this experiment is conducted in a freely falling elevator, the length of the water column becomes Show Answer

Q157) In a capillary tube, water rises to 3 mm. The height of water that will rise in another capillary tube having one-third radius of the first is Show Answer

Q158) Kerosene oil rises up the wick in a lantern Show Answer

Q159) Water rises against gravity in a capillary tube when its one end is dipped into water because Show Answer

Q160) A capillary tube of radius R is immersed in water and water rises in it to a height H. Mass of water in the capillary tube is M. If the radius of the tube is doubled, mass of water that will rise in the capillary tube will now be Show Answer

Q161) Water rises up to a height h in a capillary tube of certain diameter. This capillary tube is replaced by a similar tube of half the diameter. Now the water will rise to the height of Show Answer

Q162) There is a horizontal film of soap solution. On it a thread is placed in the form of a loop. The film is pierced inside the loop and the thread becomes a circular loop of radius R. If the surface tension of the loop be T, then what will be the tension in the thread Show Answer

Q163) A large number of water drops each of radius r combine to have a drop of radius R. If the surface tension is T and the mechanical equivalent of heat is J, then the rise in temperature will be Show Answer

Q164) An air bubble in a water tank rises from the bottom to the top. Which of the following statements are true Show Answer

Q165) In a surface tension experiment with a capillary tube water rises upto 0.1 m. If the same experiment is repeated on an artificial satellite, which is revolving around the earth, water will rise in the capillary tube upto a height of Show Answer

Q166) The correct curve between the height or depression h of liquid in a capillary tube and its radius is Show Answer

Q167) A soap bubble is blown with the help of a mechanical pump at the mouth of a tube. The pump produces a certain increase per minute in the volume of the bubble, irrespective of its internal pressure. The graph between the pressure inside the soap bubble and time t will be- Show Answer

Q168) Which graph represents the variation of surface tension with temperature over small temperature ranges for water Show Answer

Q169) Assertion :
It is easier to spray water in which some soap is dissolved.
Reason :

Q170) Assertion :
It is better to wash the clothes in cold soap solution.
Reason :
The surface tension of cold solution is more than the surface tension of hot solution.

Q171) Assertion : When height of a tube is less than liquid rise in the capillary tube, the liquid does not overflow.
Reason :
Product of radius of meniscus and height of liquid in capillary tube always remains constant.

Q172) Assertion :
A needle placed carefully on the surface of water may float, whereas a ball of the same material will always sink.
Reason :
The buoyancy of an object depends both on the material and shape of the object.

Q173) Assertion :
A large force is required to draw apart normally two glass plates enclosing a thin water film.
Reason :
Water works as glue and sticks two glass plates.

Q174) Assertion :
The impurities always decrease the surface tension of a liquid.
Reason :
The change in surface tension of the liquid depends upon the degree of contamination of the impurity.

Q175) Assertion :
The angle of contact of a liquid decrease with increase in temperature.
Reason :
With increase in temperature, the surface tension of liquid increase.

Q176) Assertion :
The concept of surface tension is held only for liquids.
Reason :
Surface tension does not hold for gases.

Q177) Assertion :
At critical temperature, surface tension of a liquid becomes zero.
Reason :
At this temperature, intermolecular forces for liquids and gases become equal. Liquid can expand without any restriction.

Q178) Assertion :
A large soap bubble expands while a small bubble shrinks, when they are connected to each other by a capillary tube.
Reason :
The excess pressure inside bubble (or drop) is inversely proportional to the radius.

Q179) Assertion :
Tiny drops of liquid resist deforming forces better than bigger drops.
Reason :
Excess pressure inside a drop is directly proportional to surface tension.

Q180) Assertion :
The water rises higher in a capillary tube of small diameter than in the capillary tube of large diameter.
Reason :
Height through which liquid rises in a capillary tube is inversely proportional to the diameter of the capillary tube.

Q181) Assertion :
Hot soup tastes better than the cold soup.
Reason :
Hot soup has high surface tension and it does not spread properly on our tongue.

Q182) Assertion :
The shape of a liquid drop is spherical.
Reason :
The pressure inside the drop is greater than that of outside.

Q183) Energy required to form a soap bubble of diameter 20 cm will be (Surface tension for soap solution is 30 dynes/cm) Show Answer

Q184) If the work done in blowing a bubble of volume V is W, then the work done in blowing the bubble of volume 2V from the same soap solution will be Show Answer

Q185) Excess pressure inside a soap bubble is three times that of the other bubble, then the ratio of their volumes will be Show Answer

Q186) When a capillary tube is dipped in water it rises upto 8 cm in the tube. What happens when the tube is pushed down such that its end is only 5 cm above the outside water level Show Answer

Q187) A bubble of 8 mm diameter is formed in the air. The surface tension of soap solution is 30 dynes/cm. The excess pressure inside the bubble is Show Answer

Q188) The height upto which water will rise in a capillary tube will be Show Answer

Q189) A drop of water breaks into two droplets of equal size. In this process, which of the following statement is correct Show Answer

Q190) A soap bubble of radius R is blown. After heating the solution a second bubble of radius 2R is blown. The work required to blow the second bubble in comparison to that required for the first bubble is Show Answer

Q191) A false statement is Show Answer

Q192) Water rises to a height of 16.3 cm in a capillary of height 18 cm above the water level. If the tube is cut at a height of 12 cm Show Answer