Vernier Caliper & Screw Gauge — Practice Questions

Free NEET Physics multiple-choice questions on Vernier Caliper & Screw Gauge. Attempt each question and reveal the answer with a full explanation.

In the Lassaigne's test for the detection of nitrogen, the Prussian blue color is due to the formation of which complex? Fe 4[Fe(CN) 6] 3 Fe 3[Fe(CN) 6] 2 Fe[Fe(CN) 6] Na 3[Fe(CN) 6] In the 'Layer Test' for halides, a salt solution is treated with CS 2 (or CCl 4 ) and chlorine water. If the organic layer turns orange, it indicates the presence of: Bromide Iodide Chloride Fluoride In the preparation of Mohr's salt, a small amount of dilute sulphuric acid is added during the dissolution of ferrous sulphate in water to: Prevent the hydrolysis of Fe 2+ ions Increase the rate of crystallization Make the salt more soluble Act as a dehydrating agent The use of HNO 3 is avoided in the detection of anions like chloride or bromide because: It is a strong oxidizing agent and can oxidize the anions to free halogens It is a weak acid and cannot displace other acids It forms explosive mixtures with organic salts It makes the solution too basic A yellow precipitate formed by adding potassium chromate ( K 2CrO 4 ) to a salt solution, which is insoluble in acetic acid but soluble in HCl , indicates the presence of: Ba 2+ Sr 2+ Ca 2+ Pb 2+ In the detection of the -CONH2 group, the substance is heated with NaOH . The gas evolved turns red litmus blue. On adding HCl and NaNO 2 at low temp followed by alkaline -naphthol, no dye is formed. This confirms: Aliphatic amide Aromatic amine Aromatic amide Nitro compound A mixture of Benzaldehyde and Acetophenone can be distinguished by: Fehling's solution Iodoform test Tollen's reagent Both Tollen's reagent and Iodoform test The Zeisel method is quantitatively used for the estimation of which of the following functional groups? Alkoxy groups ( -OCH 3 ) Nitro groups ( -NO 2 ) Amino groups ( -NH 2 ) Carboxyl groups ( -COOH ) During the 'Lake Test' for the confirmation of Al 3+ ions, the blue color of the precipitate is due to: Adsorption of blue litmus by Al(OH) 3 precipitate Formation of a complex [Al(H 2O) 6] 3+ Formation of cobalt aluminate Precipitation of aluminium phosphate What is the role of the 'Soda Extract' (Sodium Carbonate Extract) in the qualitative analysis of anions? To convert insoluble salts into soluble sodium salts of the anions To neutralize the acidity of the original mixture To act as a catalyst for the precipitation of anions To oxidize the anions to a higher oxidation state In the group analysis of cations, Ni 2+ is confirmed by adding Dimethylglyoxime (DMG) in the presence of NH 4OH . The resulting rosy red precipitate is a complex with the formula: [Ni(DMG) 2] [Ni(DMG) 3]Cl 2 [Ni(H 2O) 4(DMG)] [Ni(DMG) 4] In the Dumas method for the estimation of nitrogen, a copper gauze is placed at the exit end of the combustion tube. Its primary purpose is to: Reduce any oxides of nitrogen back to free nitrogen gas Oxidize organic vapors to CO 2 and H 2O Absorb excess oxygen gas Cool down the exiting gases before they reach the nitrometer In a meter bridge, if the balance point is found at l = 40 cm with a standard resistance R = 12 , in the left gap, the unknown resistance S in the right gap is: 18 , 8 , 12 , 20 , Seliwanoff's test is used to distinguish between: Aldoses and Ketoses Monosaccharides and Disaccharides Reducing and Non-reducing sugars Starch and Cellulose In the Hinsberg test, a secondary amine reacts with benzenesulphonyl chloride to yield a product that is: Insoluble in alkali Soluble in alkali Soluble in water but insoluble in ether A gas that turns lime water milky Libermann's Nitroso test is used for the identification of: Secondary amines Primary aliphatic amines Tertiary amines Primary aromatic amines The composition of the 'glassy bead' formed during the Borax Bead test is a mixture of: NaBO 2 and B 2O 3 Na 2B 4O 7 and H 3BO 3 NaBO 2 and NaOH B 2O 3 and H 2O During the preparation of Ferric Hydroxide sol, the method used is: Hydrolysis of FeCl 3 with boiling water Double decomposition of FeCl 3 and NaOH Mechanical dispersion of Fe(OH) 3 in water Peptization of FeCl 3 using NH 4OH The addition of ammonium molybdate solution to a solution containing phosphate ions in the presence of concentrated HNO 3 yields a yellow precipitate of: Ammonium phosphomolybdate Molybdenum phosphate Ammonium phosphate Molybdic acid When potassium chromate ( K 2CrO 4 ) is added to a solution of a salt, a yellow precipitate is formed. This precipitate is soluble in NaOH but insoluble in acetic acid. The cation present is: Pb 2+ Ba 2+ Ca 2+ Sr 2+ In a titration of a strong acid ( HCl ) with a strong base ( NaOH ), which of the following indicators would be suitable? Both Phenolphthalein and Methyl orange Only Phenolphthalein Only Methyl orange Starch solution In the extraction of anions, why is the soda extract acidified with HNO 3 before adding AgNO 3 for the chloride test? To decompose the excess Na 2CO 3 and prevent the precipitation of Ag 2CO 3 To oxidize the chloride ions to chlorine gas To increase the solubility of AgCl To act as a catalyst for the silver mirror formation A screw gauge has a pitch of 0.5 mm and there are 50 divisions on its circular scale. The instrument reads -0.03 mm when the jaws are closed. While measuring the thickness of a plate, the main scale reads 2.5 mm and the 20 th division of the circular scale coincides with the reference line. The correct thickness is: 2.73 mm 2.67 mm 2.70 mm 2.50 mm While using a Post Office Box, if the galvanometer shows a deflection to the left for R = 12 , and to the right for R = 13 , , the actual unknown resistance is: Between 12 , and 13 , Exactly 12.5 , Less than 12 , More than 13 , Schiff's reagent is used to detect the aldehyde group. Chemically, it is: Magentaline solution decolourised by SO 2 Ammoniacal silver nitrate solution Alkaline solution of copper sulphate and Rochelle salt Solution of I 2 in KI In the Victor Meyer's test, a primary alcohol gives a characteristic color after treatment with HNO 2 , NaOH , and I 2/P . The color is: Blood Red Blue Colorless Green In the 'Blue Lake' test for Al 3+ , the blue color is due to the adsorption of litmus by: Al(OH) 3 Al 2(SO 4) 3 AlCl 3 Na[Al(OH) 4] Why is concentrated HCl used instead of H 2SO 4 or HNO 3 while performing the flame test for basic radicals? Metal chlorides are more volatile than other salts Chlorides are easier to ionize HCl acts as a reducing agent HCl prevents the oxidation of the metal Which of the following compounds gives a positive test with Tollen's reagent but a negative test with Fehling's solution? Benzaldehyde Acetaldehyde Glucose Fructose The reagent used to distinguish between Primary, Secondary, and Tertiary amines by observing the solubility of their sulfonamide products in alkali is: Benzenesulphonyl chloride Acetyl chloride Nitrous acid Thionyl chloride During the qualitative analysis of Group II cations ( Cu 2+ , Pb 2+ , Cd 2+ , etc. ), H 2S gas is passed in the presence of dilute HCl . The role of HCl is to: Suppress the ionization of H 2S due to common ion effect Increase the concentration of S 2- ions Oxidize the cations to higher oxidation states Act as a catalyst for the precipitation Which of the following does NOT give the Beilstein test for halogens? Fluorine Chlorine Bromine Iodine In the estimation of nitrogen by the Dumas method, 0.5 g of an organic compound gave 60 mL of nitrogen at STP. The percentage of nitrogen in the compound is approximately: 15.0 % 28.0 % 7.5 % 12.5 % In a meter bridge experiment for the determination of resistivity, the balance point l is found. If the radius of the wire is doubled, the resistivity of the material will: Remain unchanged Become double Become half Become one-fourth The reagent used for detecting the presence of a phenolic group is: Neutral FeCl 3 solution Tollen's reagent Schiff's reagent Molisch's reagent When using a potentiometer to find the internal resistance r of a cell, the balance lengths are l 1 (open circuit) and l 2 (closed circuit with external resistance R ). The internal resistance is calculated as: r = R ( l 1 - l 2 l 2 ) r = R ( l 1 + l 2 l 1 ) r = R ( l 2 l 1 - l 2 ) r = R ( l 1 l 2 ) To convert a galvanometer of resistance G into an ammeter of range 0 to I , a shunt resistance S is connected in parallel. If I g is the full-scale deflection current, then S equals: I g G I - I g (I - I g)G I g I g I G G I - I g Which of the following carboxylic acids gives a positive Tollen's test, acting similarly to an aldehyde? Formic acid ( HCOOH ) Acetic acid ( CH 3COOH ) Oxalic acid ( H 2C 2O 4 ) Benzoic acid ( C 6H 5COOH ) Which electronic component's characteristic curve shows a sharp increase in current at a specific negative voltage (breakdown voltage) when reverse-biased? Zener Diode Photo Diode Light Emitting Diode Simple P-N Junction Diode The fluorescein test is used to detect the presence of the Phthalic anhydride group. When heated with Resorcinol and a few drops of conc. H 2SO 4 , followed by treatment with NaOH , it produces a solution with a: Green fluorescence Blood red color Deep blue precipitate Yellow oily layer During the process of Saponification (preparation of soap), common salt ( NaCl ) is added to the reaction mixture to: Precipitate the soap (salting out) Neutralize the excess NaOH Act as a catalyst for the hydrolysis of fats Increase the solubility of glycerol A spherometer has a circular scale with 100 divisions and a pitch of 1 mm . While measuring the radius of curvature of a convex mirror, the spherometer shows a reading of h = 0.5 mm . If the distance between any two legs is l = 3 cm , the radius of curvature R is calculated using: R = l 2 6h + h 2 R = l 2 3h + h R = l 2 6h R = l 2 h + h 6 The sensitivity of a meter bridge is maximum when the balance point is obtained: Near the middle of the bridge wire ( 50 cm ) Near the zero end of the wire Near the 100 cm end of the wire Does not depend on the balance point In the study of the rate of reaction between Iodine and Acetone, the reaction is typically monitored by titrating the unreacted iodine against a standard solution of: Sodium thiosulphate ( Na 2S 2O 3 ) Potassium permanganate ( KMnO 4 ) Oxalic acid Sodium hydroxide ( NaOH ) The Xanthoproteic test is used to detect proteins containing which specific type of amino acid residues? Aromatic amino acids (e.g., Tyrosine, Tryptophan) Basic amino acids (e.g., Lysine) Sulphur-containing amino acids (e.g., Cysteine) Acidic amino acids (e.g., Aspartic acid) During the flame test, a brick-red color is imparted to the flame by which cation? Ca 2+ Sr 2+ Ba 2+ Cu 2+ In the analysis of Group IV cations ( Co 2+ , Ni 2+ , Mn 2+ , Zn 2+ ), the addition of NaOH and H 2O 2 to the precipitate of MnS (dissolved in HCl ) produces a characteristic color due to the formation of MnO 2 . The color of the MnO 2 precipitate is: Black/Brown White Pink Green In the input characteristics of a common-emitter transistor, the graph is plotted between: Base current ( I B ) and Base-Emitter voltage ( V BE ) Collector current ( I C ) and Collector-Emitter voltage ( V CE ) Base current ( I B ) and Collector-Emitter voltage ( V CE ) Collector current ( I C ) and Base-Emitter voltage ( V BE ) In a Vernier caliper, the zero of the Vernier scale lies to the left of the zero of the main scale when the jaws are closed. If the 4th division of the Vernier scale coincides with a main scale division, and the least count is 0.01 cm , the zero error is: -0.06 cm +0.04 cm -0.04 cm +0.06 cm In a potentiometer experiment, the balancing length with a cell is 560 cm . When an external resistance of 10 , is connected in parallel to the cell, the balancing length changes to 400 cm . The internal resistance of the cell is: 4.0 , 2.5 , 4.5 , 0.4 , In the 'Half-Deflection Method' to find the resistance of a galvanometer ( G ), the shunt resistance required to reduce the deflection to half is S . If the resistance connected in series with the galvanometer and battery is R , then G is given by: RS R - S RS R + S R - S S In Searle's apparatus for the determination of Young's modulus, the purpose of the 'reference wire' is: To compensate for the expansion of the wire due to temperature changes and yielding of the support To double the sensitivity of the spherometer To ensure the wire is perfectly vertical To measure the original length of the experimental wire A multimeter is used to identify the terminals of a transistor. In the case of an NPN transistor, when the positive lead of the multimeter (in resistance mode) is connected to the base and the negative lead to either the emitter or collector, the multimeter shows: Low resistance High resistance Infinite resistance Zero resistance In a common emitter (CE) transistor amplifier experiment, the 'Input Resistance' ( r i ) is calculated from the slope of which graph? V BE versus I B at constant V CE I C versus V CE at constant I B V CE versus I B at constant V BE I C versus V BE at constant V CE When using a Post Office Box to measure an unknown resistance, if the ratio arms are set to 100:10 and the resistance in the rheostat arm is 125 , for balance, the unknown resistance is: 12.5 , 1250 , 1.25 , 125 , In an experiment to verify Ohm's Law, a graph of current ( I ) versus voltage ( V ) is plotted for a conductor. If the temperature of the conductor increases during the experiment, the slope of the I-V graph will: Decrease Increase Remain constant First increase then decrease The R f value in paper chromatography is defined as the ratio of: Distance moved by the substance from the baseline to the distance moved by the solvent from the baseline Distance moved by the solvent to the distance moved by the substance Total length of the paper to the distance moved by the substance Distance moved by the substance to the total length of the paper In a meter bridge experiment, the null point is l 1 = 33.7 cm . When a resistance of 12 , is connected in parallel with the unknown resistance S in the right gap, the null point shifts to 51.9 cm . This experiment demonstrates: The change in balance point with parallel resistance The end correction of the bridge The effect of temperature on resistance The internal resistance of the battery The reverse breakdown voltage of a Zener diode is 6 V . If the input voltage to a Zener-regulated circuit varies from 10 V to 15 V , the voltage across the load (connected in parallel to Zener) will be: 6 V Varies between 6 V and 9 V 10 V 15 V A physical quantity X is related to four measurable quantities a, b, c and d as X = a 2b 3c -1 d -2 . If the percentage errors in a, b, c, d are 1 %, 2 %, 3 % and 4 % respectively, the percentage error in X is: 19 % 10 % 15 % 7 % The main scale of a Vernier caliper is graduated in mm . 10 divisions of the Vernier scale coincide with 9 divisions of the main scale. While measuring the diameter of a rod, the zero of the Vernier scale is slightly to the right of the 3.2 cm mark, and the 4 th Vernier division coincides with a main scale division. The diameter is: 3.24 cm 3.204 cm 3.28 cm 3.6 cm In a meter bridge experiment, a student finds the null point at 40 cm from the left. When the unknown resistance X (in left gap) is heated, the null point will: Shift towards the right Shift towards the left Remain at 40 cm Disappear In the output characteristics of a Common Emitter transistor, if the collector current I C changes from 2 mA to 5 mA as the base current I B changes from 20 A to 50 A at constant V CE , the current gain ac is: 100 150 250 50 In an experiment to determine Young's modulus ( Y ), the load-extension graph is a straight line passing through the origin. The slope of this graph ( F vs L ) is equal to: YA / L YL / A AL / Y Y / AL In an experiment to find the resistance temperature coefficient of a wire, the resistance is 100 , at 0 C and 120 , at 100 C . The value of is: 0.002 , C -1 0.02 , C -1 0.005 , C -1 0.01 , C -1 The resistance of a conductor is measured as R = (10.0 0.1) , and the current is I = (2.00 0.01) A . The error in the calculated power P = I 2R is approximately: 2 % 3 % 1 % 0.5 % In a Vernier caliper, 20 divisions of the Vernier scale coincide with 19 divisions of the main scale. If each main scale division is 0.5 mm , what is the least count of the instrument? 0.025 mm 0.05 mm 0.01 mm 0.005 mm In the Tollen's test for aldehydes, the silver mirror is formed due to the reduction of silver ions to metallic silver. What is the composition of the Tollen's reagent? Ammoniacal silver nitrate solution Alkaline solution of copper sulphate and sodium potassium tartrate Alkaline solution of copper sulphate and sodium citrate A solution of iodine in potassium iodide The radius of a sphere is measured as r = (5.3 0.1) cm . The percentage error in the measurement of its volume is approximately: 5.66 % 1.88 % 3.77 % 2.15 % In the experiment to determine the 'Figure of Merit' of a galvanometer, the resistance of the galvanometer G is 50 , . A series resistance R = 10000 , and a battery of 2 V produce a deflection of 20 divisions. The figure of merit ( k ) is: 10 A/div 2 A/div 5 A/div 20 A/div A screw gauge with a pitch of 1 mm and 100 divisions on the circular scale is used to measure the thickness of a plate. When the jaws are closed, the 95 th division of the circular scale coincides with the reference line. The zero error is: -0.05 mm +0.05 mm -0.95 mm +0.95 mm From the output characteristics of a common-emitter transistor, the 'Output Resistance' ( r o ) is calculated as: [ V CE / I C] at constant I B [ V BE / I B] at constant V CE [ I C / I B] at constant V CE [ V CE / I B] at constant I C In a Vernier caliper, 1 cm on the main scale is divided into 10 equal parts. If 20 divisions of the Vernier scale coincide with 18 divisions of the main scale, the least count of the caliper is: 0.01 cm 0.02 cm 0.05 cm 0.001 cm In an experiment to determine Young's Modulus using Searle's apparatus, two wires of the same material and length L are used. If wire A has radius r and wire B has radius 2r , and the same load M is applied, the ratio of extensions l A / l B is: 4 2 1/2 1/4 A galvanometer with a scale divided into 100 equal divisions has a current sensitivity of 10 divisions per mA and a voltage sensitivity of 2 divisions per mV. The resistance of the galvanometer is: 5 , 20 , 50 , 2 , A student observes a 'zero error' in a screw gauge such that when the jaws are closed, the 5 th division of the circular scale is below the reference line. This is a: Positive zero error of 5 LC Negative zero error of 5 LC Positive zero error of 5 mm Negative zero error of 5 mm While using a Post Office Box to measure an unknown resistance, if the bridge is balanced at 1200 , with ratio arms 1000:10 , the unknown resistance is: 12 , 120 , 120000 , 1.2 , The dimensions of a cuboid are l = 10.0 0.1 cm , b = 5.0 0.1 cm , h = 2.0 0.1 cm . The percentage error in its volume is: 8 % 3 % 5 % 10 % During the estimation of carbon and hydrogen by Liebig's method, the water produced is absorbed in a U-tube containing: Anhydrous calcium chloride Potassium hydroxide solution Concentrated sulphuric acid Silica gel In a Vernier caliper, 10 divisions of the Vernier scale coincide with 11 divisions of the main scale. If the value of one main scale division is 1 mm , what is the least count of this 'retrograde' Vernier instrument? 0.1 mm 0.01 mm 1.1 mm 0.9 mm In Searle's apparatus for the determination of Young's modulus, two wires of the same material and same length are used (Reference wire and Experimental wire). The primary purpose of using the reference wire is to: Compensate for errors due to thermal expansion and support sag Provide a baseline for measuring the diameter of the experimental wire Increase the load-bearing capacity of the frame Serve as a backup in case the experimental wire breaks A student uses a spherometer to find the thickness of a glass strip. If the pitch is 0.5 mm and the circular scale has 50 divisions, what is the 'Sagitta' h if the circular scale reading is 30 divisions (after 2 complete rotations of the screw from the base level)? 1.30 mm 1.15 mm 1.00 mm 0.30 mm Which of the following describes the correct procedure for using a multimeter to check if a capacitor is functioning? Set to resistance mode; the reading should start low and increase to infinity. Set to DC voltage mode; the reading should be a constant non-zero value. Set to AC current mode; the reading should be zero. Set to continuity mode; it should beep continuously. Which of the following is the correct expression for the 'Voltage Gain' ( A v ) of a Common Emitter transistor amplifier in terms of current gain , load resistance R L , and input resistance r i ? A v = (R L / r i) A v = (r i / R L) A v = (R L / r i) A v = 1 / ( R L) In the input characteristics of a common-emitter transistor, if the base-emitter voltage V BE is increased while keeping V CE constant, the base current I B : Increases exponentially Decreases linearly Remains constant Increases linearly A physical quantity P is given by P = A 3 B 1/2 / C . The percentage errors in A, B, and C are 1 %, 2 %, and 3 % respectively. The maximum percentage error in P is: 7 % 6 % 4 % 9 % Which logic gate is equivalent to the circuit formed by connecting two NAND gates in a way that the output of the first is split and fed into both inputs of the second? AND OR NOR XOR In a vernier callipers, (N + 1) divisions of vernier scale coincide with N divisions of main scale. If 1 MSD represents 0.1 mm, the vernier constant (in cm) is: 1 10N 1 100(N + 1) 100 N 10 (N + 1) Consider the diameter of a spherical object being measured with the help of a Vernier callipers. Suppose its 10 Vernier Scale Divisions (V.S.D.) are equal to its 9 Main Scale Divisions (M.S.D.). The least division in the M.S. is 0.1 cm and the zero of V.S. is at x = 0.1 cm when the jaws of Vernier callipers are closed. If the main scale reading for the diameter is M = 5 cm and the number of coinciding vernier division is 8, the measured diameter after zero error correction, is 5.00 cm 5.18 cm 5.08 cm 4.98 cm In the preparation of Lyophilic sol like starch, why is the starch paste added to boiling water with constant stirring? To ensure small particle size and prevent clump formation To increase the charge on the particles To decrease the viscosity of the sol To oxidize the starch In the test for the Phosphate radical ( PO 4 3- ), a yellow precipitate is obtained on adding ammonium molybdate and concentrated HNO 3 . The formula of the yellow precipitate is: (NH 4) 3PO 4 12MoO 3 (NH 4) 2MoO 4 Mg(NH 4)PO 4 H 3PO 4 12MoO 3 The presence of Tyrosine in a protein sample is confirmed by which test? Millon's test Xanthoproteic test Molisch test Biuret test In the systematic analysis of cations, why must interfering radicals like Phosphate or Oxalate be removed before proceeding to Group III? They form precipitates with Group III reagents, interfering with the detection of Fe 3+ , Al 3+ , and Cr 3+ They make the solution highly acidic, preventing precipitation They oxidize the NH 4OH reagent They prevent the formation of the Sodium Carbonate extract During the qualitative analysis of Group IV cations ( Co 2+ , Ni 2+ , Mn 2+ , Zn 2+ ), H 2S gas is passed through an ammoniacal solution. Why is NH 4Cl added before NH 4OH ? To suppress the ionization of NH 4OH by common ion effect to prevent the precipitation of Group V cations To increase the concentration of OH - ions To decrease the solubility product of the metal sulphides To convert the metal ions into their respective chlorides A student performs a back titration to find the concentration of an NH 3 solution. 25 mL of 0.1 M HCl is added to 10 mL of NH 3 solution. The excess HCl requires 10 mL of 0.05 M NaOH for neutralization. The molarity of NH 3 is: 0.20 M 0.15 M 0.25 M 0.10 M While measuring the radius of curvature R of a convex mirror using a spherometer, the distance between the legs is l = 4.0 cm and the sagitta is h = 0.08 cm . The value of R is approximately: 33.37 cm 16.68 cm 25.04 cm 42.12 cm A potentiometer wire of length 100 cm has a resistance of 10 , . It is connected in series with a resistance and a cell of EMF 2 V and negligible internal resistance. A source of EMF 10 mV is balanced against a length of 40 cm of the potentiometer wire. What is the value of the external series resistance? 790 , 810 , 400 , 100 , The length, breadth, and thickness of a block are measured as 125.1 cm , 5.0 cm , and 0.32 cm respectively. Which measurement is least accurate? Thickness Breadth Length All are equally accurate One main scale division of a Vernier calliper is equal to 1 mm and the number of divisions on the Vernier scale is 10 . When both the jaws touch each other, the Vernier scale shifts to the left of zero of the main scale in such a way that 4th Vernier division coincides with a division of the main scale. If this Vernier calliper measures the length of the wire to be 1 cm, the actual length of the wire is: 0.60 cm 0.96 cm 1.00 cm 1.04 cm The Molisch test gives a characteristic violet/purple ring at the junction of two layers. This test is positive for: All Carbohydrates Only Amino Acids Only Fatty Acids Only Phenols Which gas is evolved when a carbonate salt is treated with dilute HCl ? CO 2 CO O 2 H 2 The red vapors produced in the Chromyl Chloride test have the chemical formula: CrO 2Cl 2 CrCl 3 CrO 3 Cr 2O 2Cl 2 In the ring test for nitrate radical, the brown color of the ring is due to the formation of: [Fe(H 2O) 5(NO)] 2+ [Fe(H 2O) 4(NO) 2] 2+ [Fe(H 2O) 5(NO)] 3+ Fe 2(SO 4) 3 Which of the following compounds will give a positive Iodoform test when treated with I 2 and NaOH ? Pentan-2-one Pentan-3-one Benzaldehyde Methanol Ninhydrin reagent is used to detect the presence of which of the following in a given sample? Amino acids Carbohydrates Fixed oils Alkaloids The R f (retardation factor) value in chromatography is always: Between 0 and 1 Greater than 1 Equal to 1 Between -1 and 0 Which of the following organic compounds will evolve CO 2 gas with an aqueous solution of sodium bicarbonate ( NaHCO 3 )? Benzoic acid Phenol Ethyl alcohol Benzaldehyde In a Vernier caliper, N divisions of the Vernier scale coincide with (N-1) divisions of the main scale. If the value of one main scale division is 1 mm , what is the least count of the instrument? 1/N mm (N-1)/N mm 1/(N-1) mm 1/N 2 mm In a meter bridge experiment, the null point is obtained at a distance l from the left end. If the resistance in the left gap is X and in the right gap is Y , and they are interchanged, the new null point is at l' . Which of the following is true? l' = 100 - l l' = l l' = 1/l l' = 50 + l Sensitivity of a potentiometer can be increased by: Increasing the length of the potentiometer wire Increasing the potential gradient Decreasing the length of the potentiometer wire Increasing the current in the primary circuit The figure of merit of a galvanometer is defined as: The current required to produce a deflection of one scale division The voltage required to produce unit deflection The reciprocal of current sensitivity The maximum current the galvanometer can sustain In the half-deflection method for finding galvanometer resistance, if the resistance R in series with the battery is very large compared to G , and the shunt S produces half deflection, then: G = S G = R G = 2S G = S/2 Which of the following measurements is most precise? 5.00 mm 5.0 mm 5.000 cm 5.0 cm Which of the following observations is correct for the Biuret test used for detecting proteins? Violet or purple color Brick red precipitate Yellow precipitate Silver mirror During the identification of the chloride ion ( Cl - ) in qualitative analysis, AgNO 3 is added to the acidified extract. The resulting white precipitate of AgCl is soluble in: Excess NH 4OH Dilute HCl Dilute HNO 3 Cold water In the flame test, a crimson red color is characteristic of which of the following cations? Sr 2+ Ba 2+ Ca 2+ Cu 2+ When neutral ferric chloride solution is added to an aqueous solution of phenol, a characteristic color is observed. This color is: Violet Green Red Blue In the test for the oxalate ion ( C 2O 4 2- ), the salt is treated with dilute H 2SO 4 and warmed, followed by the addition of KMnO 4 . The observation is: Purple color of KMnO 4 is discharged with evolution of CO 2 A brown ring is formed A white precipitate of CaC 2O 4 forms A pungent smelling gas is evolved Which of the following gases turns a filter paper soaked in lead acetate solution black? H 2S SO 2 CO 2 NH 3 In chromatography, if the distance moved by the solvent is 10 cm and the distance moved by the compound is 6 cm , the retardation factor ( R f ) is: 0.6 1.67 60 0.4 The least count of a spherometer is given by the formula: Pitch / Number of divisions on the circular scale Pitch Number of divisions on the circular scale Value of one MS division - Value of one VS division Pitch / Length of the spherometer leg The reagent used to distinguish between aldehydes and ketones is: Tollen's reagent 2,4-DNP Lucas reagent Neutral FeCl 3 The 'backlash error' in instruments like the screw gauge or spherometer is reduced by: Rotating the screw in only one direction for a measurement Cleaning the threads with oil Using a screw with a larger pitch Reducing the number of divisions on the scale During the preparation of Potash Alum ( K 2SO 4 Al 2(SO 4) 3 24H 2O ), the shape of the crystals obtained is: Octahedral Monoclinic Rhombic Needle-shaped In the Borax bead test, a cobalt salt produces a bead of which color in both oxidizing and reducing flames? Deep Blue Green Bottle Green Colorless In the qualitative analysis of basic radicals, the flame test for Potassium salts produces a color described as: Lilac (Pale Violet) Apple Green Golden Yellow Brick Red A student determines the purity of an organic compound. Which physical property measurement is most commonly used as a primary criterion for the purity of a solid compound? Sharpness of the melting point Density Refractive index Boiling point In the preparation of an ester (e.g., Ethyl Acetate), concentrated H 2SO 4 is added to the mixture of alcohol and carboxylic acid. Its primary role is: Both as a catalyst and a dehydrating agent Only as a solvent Only to increase the boiling point As an oxidizing agent Which principle is the basis for Column Chromatography used in the separation of components in a mixture? Differential adsorption Differential solubility in water Difference in boiling points Difference in molecular weights A screw gauge gives the following readings when used to measure the diameter of a wire: Main scale reading = 0 mm , Circular scale reading = 52 divisions . Given that 1 mm on main scale corresponds to 100 divisions of the circular scale, the diameter of the wire is: 0.052 cm 0.52 cm 0.026 cm 0.0052 cm In the Dumas method for estimation of nitrogen, the gas collected in the nitrometer is: N 2 NH 3 NO 2 NO While performing an experiment with a metre bridge, a student finds the null point at distance l from the left end. To reduce 'end errors' in this experiment, the most effective step is to: Adjust the resistances so that the null point is near the center of the wire Use a thicker bridge wire to increase resistance Increase the EMF of the driver cell Interchange the positions of the galvanometer and the cell The resistance of a wire is R = V I , where V = (100 5) V and I = (10 0.2) A . The percentage error in R is: 7 % 5 % 2 % 10 % A multimeter cannot be used to measure which of the following? Phase difference DC current Resistance AC voltage Which of the following logic gates is represented by the following truth table? (Inputs: A, B; Output: Y) | A:0, B:0 -> Y:1 | A:0, B:1 -> Y:1 | A:1, B:0 -> Y:1 | A:1, B:1 -> Y:0 | NAND NOR AND OR The figure of merit of a galvanometer is 0.02 mA/division . If the galvanometer has 30 divisions on either side, the current required to produce full-scale deflection is: 0.6 mA 0.02 mA 1.5 mA 6.0 mA Which of the following errors is categorized as a 'Systematic Error'? Zero error in a micrometer Unpredictable fluctuations in temperature during an experiment Random vibrations of the experimental setup Error due to the observer's lack of concentration To convert a galvanometer into a voltmeter of range 0-V , a high resistance R is connected in series. If G is the resistance of the galvanometer and I g is the current for full-scale deflection, then R is: (V/I g) - G (V/I g) + G V / (I g + G) (I g/V) - G Nessler's reagent is used to detect: NH 4 + Cr 3+ Al 3+ Pb 2+ In an experiment to measure the thickness of a small glass plate, a student uses a screw gauge with 50 circular scale divisions and a pitch of 0.5 mm . If the glass plate is measured at 5 different locations and the average thickness is 2.40 mm , the maximum possible relative error is related to: The least count of the screw gauge The number of measurements taken The total length of the screw gauge The pressure applied to the thimble A spherometer is used to measure the radius of curvature R of a spherical surface. If l is the average distance between the legs and h is the spherometer reading (sagitta), R is given by: R = l 2 6h + h 2 R = l 2 h + h 2 R = l 2 3h + h R = l 2 2h + h 6 In a measurement, the value of a length is 0.003020 m . The number of significant figures in this value is: 4 3 6 5 The 'backlash error' in a screw gauge is usually caused by: Wear and tear or loose fitting of the screw threads Expansion of the screw due to temperature Non-uniformity of the circular scale Improper alignment of the spindle In a moving coil galvanometer, the deflection is proportional to the current I as I = K . The 'current sensitivity' is defined as: / I I / K / / V In a potentiometer, the potential gradient of the wire is 2 mV/cm . The EMF of a cell which is balanced at 150 cm is: 0.3 V 300 V 3 V 0.03 V Which logic gate's output is 'high' only when both inputs are 'low'? NOR NAND OR AND The formula of the white precipitate formed when AgNO 3 reacts with a chloride salt is: AgCl Ag 2Cl [Ag(NH 3) 2]Cl AgClO 3 In a meter bridge experiment, the purpose of using a thick copper strip to connect the resistances is to: Minimize the resistance of the connections Increase the sensitivity of the bridge Prevent heating of the circuit Protect the galvanometer Aniline is usually purified by steam distillation. This is because aniline: Is steam volatile and immiscible with water Has a boiling point lower than water Reacts with water to form a stable complex Is soluble in hot water but insoluble in cold water The following truth table corresponds to which logic gate? (Inputs A, B; Output Y): | 0,0 -> 1 | 0,1 -> 0 | 1,0 -> 0 | 1,1 -> 0 | NOR NAND XOR AND While using a meter bridge, a student finds the null point at l = 40 cm . To improve the accuracy and minimize end errors, what should the student do? Adjust the resistances in the gaps so the null point is near 50 cm Use a longer connecting wire for the galvanometer Use a battery with a higher EMF Increase the resistance of the meter bridge wire In the Kjeldahl method, the nitrogen present in the organic compound is quantitatively converted into: (NH 4) 2SO 4 NH 3 N 2 NO 2 A Vernier caliper is used to measure the internal diameter of a beaker. The main scale reading is 4.5 cm and the 6 th Vernier division coincides with a main scale division. If the least count is 0.01 cm and there is no zero error, the internal diameter is: 4.56 cm 4.506 cm 4.65 cm 5.10 cm Which of the following elements is detected by the appearance of a violet color when treated with sodium nitroprusside solution in Lassaigne's extract? Sulphur Nitrogen Chlorine Phosphorus In a common emitter transistor circuit, if the current gain = 100 , what is the value of ? 0.99 1.01 0.90 100/101 Which of the following describes the 'parallax error' in optical experiments? Apparent shift in the position of an object relative to another when viewed from different positions Error due to the finite thickness of the lens Error due to reflection from the back surface of a mirror Error due to temperature changes in the room A screw gauge has a pitch of 0.5 mm and a circular scale with 200 divisions. The least count of the instrument is: 0.0025 mm 0.025 mm 0.005 mm 0.05 mm In a meter bridge experiment, the null point is obtained at l = 25 cm from the left end. If the resistance in the left gap is 10 , , the resistance in the right gap is: 30 , 10 , 40 , 20 , For a common emitter transistor amplifier, the current gain is 100 . If the collector current changes by 1 mA , the change in base current is: 10 A 100 A 1 mA 0.01 mA Which of the following functions does the 'ratchet' in a screw gauge perform? It prevents over-pressing of the object It moves the circular scale linearly It helps in zero error correction It locks the screw at a particular reading While calculating the value of a physical quantity P = a 3b 2/( c d) , the maximum relative error is given by: 3 a a + 2 b b + 1 2 c c + d d 3 a a 2 b b 1 2 c c d d 3 a a + 2 b b - 1 2 c c - d d a a + b b + c c + d d A student wishes to study the cell structure under a light microscope having 10X eyepiece and 45X objective. He should illuminate the object by which one of the following colours of light so as get the best possible resolution - Red Green Yellow Blue A student performs an experiment of measuring the thickness of a slab with a vernier calliper whose 50 divisions of the vernier scale are equal to 49 divisions of the main scale. He noted that zero of the vernier scale is between 7.00 cm and 7.05 cm mark of the main scale and 23rd division of the vernier scale exactly coincides with the main scale. The measured value of the thickness of the given slab using the calliper will be : 7.73 cm 7.23 cm 7.023 cm 7.073 cm A student measured the diameter of a small steel ball using a screw gauge of least count 0.001 cm. The main scale reading is 5 mm and zero of circular scale division coincides with 25 divisions above the reference level. If screw gauge has a zero error of -0.004 cm, the correct diameter of the ball is 0.053 cm 0.525 cm 0.521 cm 0.529 cm A screw gauge has least count of 0.01 mm and there are 50 divisions in its circular scale. The pitch of the screw gauge is : 0.25 mm 0.5 mm 1.0 mm 0.01 mm A screw gauge gives the following readings when used to measure the diameter of a wire Main scale reading : 0 mm Circular scale reading : 52 divisions Given that 1 mm on main scale corresponds to 100 divisions on the circular scale. The diameter of the wire from the above data is 0.026 cm 0.26 cm 0.052 cm 0.52 cm A student rounds off the following measurements to three significant figures: (i) 2.745 g and (ii) 2.735 g . The correct reported values should be: 2.74 g and 2.74 g 2.75 g and 2.74 g 2.74 g and 2.73 g 2.75 g and 2.73 g In a vernier calliper, 20 VSD coincide with 16 MSD (each division of length 1 mm). The least count of the vernier callipers is: 0.2 cm 0.1 cm 0.02 cm 0.01 cm During the estimation of nitrogen by the Kjeldahl method, which of the following compounds does not yield ammonia upon digestion with concentrated H 2SO 4 ? Pyridine Acetamide Ethylamine Glycine The presence of magnesium in a salt is confirmed by the formation of a white crystalline precipitate of which compound when treated with Na 2HPO 4 in the presence of NH 4OH ? Mg(NH 4)PO 4 Mg 3(PO 4) 2 MgHPO 4 Mg(OH) 2 In the separation of ortho and para-nitrophenols by steam distillation, which isomer is steam volatile? o-Nitrophenol p-Nitrophenol Both are equally volatile Neither is steam volatile The primary reason for using a 'guard tube' containing anhydrous calcium chloride at the end of the combustion tube in Liebig's method is to: Prevent atmospheric moisture from entering the apparatus Absorb the carbon dioxide produced Absorb the water vapor produced by the sample Act as a catalyst for the combustion A mixture of camphor and benzoic acid can be separated most effectively by: Chemical method using NaHCO 3 solution Sublimation Fraction