Surface Tension & Viscosity Experiments — Practice Questions

Free NEET Physics multiple-choice questions on Surface Tension & Viscosity Experiments. Attempt each question and reveal the answer with a full explanation.

A student performs the 'Clock Reaction' between Na 2S 2O 3 and HCl . If the temperature is increased by 10 C , the time taken for the cross marked on the paper to disappear: Decreases Increases Remains the same Becomes zero Which color is imparted to the Bunsen flame by Barium salts? Apple green Crimson red Golden yellow Lila / Violet During the titration of Oxalic acid with KMnO 4 , the reaction is slow initially but becomes fast after some time. This is because: Mn 2+ acts as an autocatalyst The solution is heated The concentration of oxalic acid increases KMnO 4 is a strong oxidizing agent In the Beilstein test for the detection of halogens in organic compounds, the appearance of which color flame indicates the presence of halogens? Green Blue Brick red Violet Which of the following silver halides is completely insoluble in both dilute and concentrated ammonia solution ( NH 4OH )? AgI AgCl AgBr AgF The addition of a detergent to water results in: Decrease in surface tension Increase in surface tension No change in surface tension Increase in viscosity but no change in surface tension The coefficient of viscosity of a liquid decreases with an increase in temperature because: The kinetic energy of molecules increases and intermolecular forces decrease The density of the liquid increases The surface tension increases The molecules become larger in size In the experiment to determine the viscosity of a liquid, a small spherical ball is dropped into a long column of the liquid. The velocity of the ball becomes constant (terminal velocity) when: Net force on the ball is zero Viscous force is maximum Weight of the ball is zero Buoyant force is zero While measuring the surface tension of water using the capillary rise method, if the height of the water column is h and the radius of the capillary is r , the surface tension T is calculated. If the experiment is repeated with a capillary of half the radius, the height of the water column will: Become 2h Remain h Become h/2 Become 4h The pressure inside a spherical drop of water of radius R is P 1 , and the outside atmospheric pressure is P 0 . If the surface tension is T , then P 1 - P 0 is: 2T/R 4T/R T/R 8T/R During the measurement of surface tension using a Stalagmometer, the number of drops is counted. If the number of drops for liquid A is more than liquid B for the same volume, then: Liquid A has lower surface tension than B Liquid A has higher surface tension than B Liquid A is more viscous than B Both liquids have the same surface tension The purple color of KMnO 4 is discharged when it reacts with an acidified solution of ferrous sulphate. In this reaction, KMnO 4 acts as: An oxidizing agent A reducing agent A catalyst A dehydrating agent The SI unit of the coefficient of viscosity ( ) is: kg m -1 s -1 kg m s -2 Poise N m -2 In the capillary rise method for surface tension ( T ), if the radius of the capillary tube is r and the height of the liquid column is h , the formula used (ignoring the weight of the meniscus) is: T = rh g 2 T = 2h g r T = r 2h g 2 T = rh g In the study of reaction kinetics (Clock Reaction) between Sodium Thiosulphate and Hydrochloric acid, the rate of reaction is measured by observing the time taken for the solution to become opaque. This opacity is due to the formation of: Colloidal Sulphur Sulphur dioxide gas Sodium Chloride crystals Hydrogen Sulphide While determining the viscosity of a highly viscous liquid by the terminal velocity method, if two different spherical balls of radii r and 2r are used, the ratio of their terminal velocities ( v 1/v 2 ) will be: 1:4 1:2 1:1 4:1 A student blows a soap bubble of radius R . If the surface tension of the soap solution is T , the work done in blowing the bubble is: 8 R 2 T 4 R 2 T 2 R 2 T 4 3 R 3 T In paper chromatography, the components of a mixture are separated based on their differential: Partition between stationary and mobile phases Adsorption on the cellulose fibers Rates of evaporation Solubility in the stationary phase only In the analysis of anions, a salt solution reacts with dilute H 2SO 4 to produce a gas that turns lime water milky. This gas also turns an acidified K 2Cr 2O 7 solution green. The anion is: SO 3 2- CO 3 2- S 2- NO 2 - In the Carius method for the estimation of halogens, 0.15 g of an organic compound gives 0.188 g of AgBr . The percentage of bromine in the compound is: (At. mass: Ag=108, Br=80 ) 53.33 % 42.50 % 60.00 % 35.25 % In the volumetric titration of Fe 2+ ions with K 2Cr 2O 7 , K 2Cr 2O 7 is preferred as a primary standard over KMnO 4 because: It is not hygroscopic and can be weighed accurately It acts as its own indicator It is a much stronger oxidizing agent It can be used in the presence of HCl In the Borax bead test, which of the following metal salts produces a green color bead in the oxidizing flame? Chromium Copper Iron Manganese In the titration of KMnO 4 against Mohrs salt, the equivalent mass of KMnO 4 in acidic medium is: M / 5 M / 3 M / 1 M / 6 In the separation of Pb 2+ and Hg 2 2+ in Group I, the mixture of chlorides is treated with hot water. Which of the following happens? PbCl 2 dissolves while Hg 2Cl 2 remains insoluble Both PbCl 2 and Hg 2Cl 2 dissolve Hg 2Cl 2 dissolves while PbCl 2 remains insoluble Both PbCl 2 and Hg 2Cl 2 remain insoluble Which of the following alcohols will give a positive Iodoform test? Ethanol Methanol 1-Propanol n-Butyl alcohol In the terminal velocity experiment for viscosity, if the density of the spherical ball is and the density of the liquid is , the ball will move upwards with terminal velocity if: > > = Never possible In the qualitative analysis of anions, why is the 'Sodium Carbonate Extract' boiled with concentrated HNO 3 before adding Silver Nitrate for the testing of halides? To decompose NaCN and Na 2S which would otherwise interfere with the test To ensure the solution is acidic enough for AgCl to precipitate To oxidize Cl - to Cl 2 gas To catalyze the reaction between Ag + and X - In the preparation of Mohr's salt, the addition of a few drops of dilute H 2SO 4 to the solution of ferrous sulphate is essential to: Prevent the hydrolysis of Fe 2+ ions to Fe(OH) 2 Increase the rate of crystallization Act as a catalyst for the formation of the double salt Ensure that the salt is anhydrous In the Dumas method for the estimation of nitrogen, the purpose of the 'Reduced Copper Gauze' at the end of the combustion tube is to: Reduce any oxides of nitrogen back to free nitrogen gas Absorb excess CO 2 gas Oxidize the organic compound completely Filter out any solid soot particles During the titration of Sodium Carbonate ( Na 2CO 3 ) against Hydrochloric acid ( HCl ), which indicator is used for the second end-point (where HCO 3 - is converted to CO 2 )? Methyl Orange Phenolphthalein Starch Potassium Chromate In the determination of the surface tension of water by the capillary rise method, if the temperature of water is increased, the height of the water column in the capillary will: Decrease Increase Remain the same First increase then decrease In the 'Blue Lake' test for Aluminium ions, what is the 'lake'? Adsorption of litmus color on the surface of Al(OH) 3 precipitate A complex formed between Al 3+ and NH 4OH A solution of AlCl 3 in water The supernatant liquid above the precipitate Which pair of cations can be separated by using H 2S gas in the presence of dilute HCl ? Cu 2+ , Ni 2+ Zn 2+ , Mn 2+ Fe 3+ , Al 3+ Ba 2+ , Ca 2+ Which gas is evolved when an ammonium salt is heated with sodium hydroxide solution, and how is it identified? Ammonia; gives dense white fumes with a glass rod dipped in conc. HCl Nitrogen; turns lime water milky Oxygen; relights a glowing splinter Hydrogen; burns with a pop sound In the estimation of sulphur by Carius method, 0.468 g of an organic compound gave 0.668 g of barium sulphate. What is the percentage of sulphur in the compound? (Atomic mass: Ba=137, S=32, O=16 ) 19.60% 25.40% 32.10% 10.20% What is the correct order of Group reagents for the systematic analysis of cations? dil. HCl H 2S/HCl NH 4OH/NH 4Cl H 2S/NH 4OH H 2S dil. HCl NH 4OH/NH 4Cl (NH 4) 2CO 3 dil. HCl NH 4OH H 2S (NH 4) 2CO 3 NH 4OH dil. HCl (NH 4) 2CO 3 H 2S In the estimation of halogen by Carius method, if 0.15 g of an organic compound gives 0.12 g of AgBr , find the percentage of bromine. (At. mass: Ag = 108, Br = 80 ) 34.04% 42.12% 25.00% 53.20% Which of the following will not give a positive Lassaigne's test for nitrogen? NH 2NH 2 CH 3NH 2 C 6H 5NH 2 NH 2CONH 2 Which of the following tests can be used to distinguish between a monosaccharide and a disaccharide? Barfoed's test Molisch's test Biuret test Seliwanoff's test In the determination of the boiling point of an organic compound, why is a capillary tube (sealed at one end) placed inverted in the liquid? To act as a visual indicator when the internal pressure equals atmospheric pressure To prevent the liquid from evaporating To stir the liquid during heating To maintain a constant temperature In the Carius method for the estimation of phosphorus, 0.5 g of an organic compound gave 1.11 g of Mg 2P 2O 7 . What is the percentage of phosphorus in the compound? (At. mass: P=31, Mg=24, O=16 ) 62% 31% 25% 12.5% In the estimation of Nitrogen by Dumas method, 0.3 g of an organic compound gave 50 mL of nitrogen collected at 300 K and 715 mm pressure. If the aqueous tension at 300 K is 15 mm, calculate the percentage of nitrogen. 17.46% 14.50% 20.30% 10.20% In the test for Nitro group (Mulliken-Barker test), the compound is reduced with Zn/NH 4Cl and then treated with Tollen's reagent. The formation of a silver mirror indicates: The presence of a nitro group The presence of an aldehyde group The presence of an alcohol group The presence of a carboxylic acid group In the estimation of nitrogen by the Kjeldahl method, which of the following compounds will NOT give a positive result despite containing nitrogen? Pyridine Acetamide Urea Glycine Which of the following organic compounds will give a positive test with Lucas reagent immediately at room temperature? 2-Methylpropan-2-ol Butan-2-ol Butan-1-ol Ethanol When neutral FeCl 3 is added to an aqueous solution of an acetate salt, a deep red color is produced. Upon boiling this solution, a reddish-brown precipitate is formed. The formula of this precipitate is: [Fe(OH) 2(CH 3COO)] Fe(OH) 3 Fe(CH 3COO) 3 [Fe 3(OH) 2(CH 3COO) 6] + During the test for the Nitro group using the Mulliken-Barker test, the compound is reduced. Which reagent is used for this reduction step? Zn + NH 4Cl solution Sn + HCl LiAlH 4 in ether H 2 / Pd In Group II of basic radical analysis, H 2S gas is passed in the presence of dilute HCl . The role of dilute HCl is to: Decrease the concentration of S 2- ions by common ion effect Increase the concentration of S 2- ions to precipitate Group IV Oxidize the cations to higher oxidation states Prevent the precipitation of Group I radicals In the analysis of Group IV cations, the addition of excess NH 4OH followed by H 2S results in a black precipitate. On adding concentrated HCl and a crystal of KClO 3 to this precipitate, followed by NaOH and Bromine water, a green solution is NOT formed, but a rosy red precipitate appears with DMG. This confirms: Ni 2+ Co 2+ Mn 2+ Zn 2+ In Poiseuille's experiment to determine the viscosity of a liquid, if the radius of the capillary tube is reduced by 50 % , the volume of liquid flowing out per second ( V ) will change by a factor of: 1/16 1/4 1/2 1/8 In the measurement of surface tension by the capillary rise method, if the experiment is performed in an elevator falling freely under gravity, the height of the liquid in the capillary will: Fill the entire length of the tube Be the same as on the ground Be zero Be half the original value The presence of a -CHO group in a compound can be confirmed by using Schiff's reagent, which turns from colorless to: Magenta / Pink Blue Green Yellow A substance on treatment with dil. H 2SO 4 gives a gas which turns acidified K 2Cr 2O 7 paper green. The anion is: SO 3 2- S 2- CO 3 2- NO 2 - Which test is used to detect the presence of Peptide bonds in a given sample? Biuret test Ninhydrin test Xanthoproteic test Millon's test Which reagent is used to separate Pb 2+ from Ag + in the first group of qualitative analysis? Hot water Ammonium hydroxide Dilute HCl Potassium iodide