Recent questions tagged 2013

In excess of $AgNO_3$ is added to 100 mL of a 0.01 M solution of dichlorotetraaquachrominum (III) chloride. The number of moles of AgCl precipitated would be-

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$XeF_2$ is isostructural with-

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Identify the correct order of solubility in aqueous medium-

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Which of the following lanthanoid ions is diamagnetic ? (At. No. Ce = 58, Sm = 62, Eu = 63, Yb = 70)

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Which of the following does not give oxygen on heating ?

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Reaction by which Benzaldehyde cannot be prepared-

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The basic structural unit of silicates is -

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Which of the following structure is similar to graphite ?

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Which of the following is paramagnetic ?

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Which is the strongest acid in the following ?

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Roasting of sulphides gives the gas X as a byproduct. This is colorless gas with choking smell of burnt sulphur and causes great damage to respiratory organs as a result of acid rain. Its aqueous solution is acidic, acts as a reducing agent and its acid has never been isolated. The gas X is -

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A magnetic moment of 1.73 BM will be shown by one among the following -

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Dipole - induced dipole interactions are present in which of the following pairs :

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A metal has a fcc lattice. The edge length of the unit cell is 404 pm. The density of the metal is $ 2.72 \; g \;cm^{–3}$. The molar mass of the metal is : [NA Avogadro's constant = $6.02 \times 10^{23} mol^{–1}$]

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Maximum deviation from ideal gas is expected from :

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The number of carbon atoms per unit cell of diamond unit cell is -

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How many grams of concentrated nitric acid solution should be used to prepare 250 mL of 2.0 M $HNO_3$ ? The concentrated acid is 70 % $HNO_3$.

asked Aug 20, 2018 by pady_1

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A button cell used in watches functions as following $Zn(s) + Ag_2O(s) + H_2O (l) \rightleftharpoons 2Ag(s) + Zn^{2+} (aq) + 2OH^- (aq)$ If half cell potentials are $Zn^{2+} (aq) + 2e^- \to Zn (s) ; \; \; \; E^o = -0.76V $ $ Ag_2O(s) + H_2O (l) + 2e^- \to 2Ag(s) + 2OH^- (aq),\; \; \; E^o = 0.34 V $ The cell potential will be -

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Based on equation $E = -2.178 \times 10^{-18} J (\frac{Z^2}{n^2})$, certain conclucsions are written. Which of them is not correct ?

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At $25^oC$ molar conductance of 0.1 molar aqueous solution of ammonium hydroxide is $9.54 \; ohm^{-1} cm^2 mol^{-1}$ and at infinite dilution its molar conductance is $238 \; ohm^{-1} cm^2 mol^{-1}$. The degree of ionisation of ammonium hydroxide at the same concentration and temperature is -

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A reaction having equal energies of activation for forward and reverse reactions has -

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A hydrogen gas electrode is made by dipping platinum wire in a solution of HCl of pH = 10 and by passing hydrogen gas around the platinum wire at one atm pressure. The oxidation potential of electrode would be ?

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What is the activation energy for a reaction if its rate doubles when the temperature is raised from $20^oC$ to $35^oC$ ? (R = 8.314 $J mol^{-1} K^{-1}$)

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What is the maximum numbers of electrons that can be associated with the following set of quantum numbers ? n = 3, l = 1 and m = -1

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The value of Planck's constant is $6.63 \times 10^{-34} Js$. The speed of light is $3 \times 10^{17} nms^{-1}$. Which value is closest to the wavelength in nanometer of a quantum of light with frequency of $6 \times 10^{15} s^{-1}$ ?

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The output (X) of the logic circuit shown in figure will be -

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In a common emitter (CE) amplifier having a voltage gain G, the transistor used has transconductance 0.03 mho and current gain 25. If the above transistor is replaced with another one with transconductance 0.02 mho and current gain 20, the voltage gain will be -

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In a n-type semiconductor, which of the following statements is true -

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A parallel beam of fast moving electrons is incident normally on a narrow slit. A fluorescent screen is placed at a large distance from the slit. If the speed of the electrons is increased, which of the following statements is correct ?

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In Young’s double slit experiment, the slits are 2mm apart and are illuminated by photons of two wavelengths $\lambda_1 = 12000 Å$ and $\lambda_2 = 10000 Å$. At what minimum distance from the common central bright fringe on the screen 2m from the slit will a bright fringe from one interference pattern coincide with a bright fringe from the other ?

asked Aug 20, 2018 by pady_1

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For a normal eye, the cornea of eye provides a converging power of 40D and the least converging power of the eye lens behind the cornea is 20D. Using this information, the distance between the retina and the corneaeye lens can be estimated to be -

asked Aug 20, 2018 by pady_1

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A plano convex lens fits exactly into a plano concave lens. Their plane surfaces are parallel to each other. If lenses are made of different materials of refractive indices $\mu_1$ and $\mu_2$ and R is the radius of curvature of the curved surface of the lenses, then the focal length of the combination is -

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The wavelength $\lambda_e$ of an electron and $\lambda_p$ of a photon of same energy E are related by -

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For photoelectric emission from certain metal the cutoff frequency is $ν$. If radiation of frequency $2ν$ impinges on the metal plate, the maximum possible velocity of the emitted electron will be (m is the electron mass) -

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A certain mass of Hydrogen is changed to Helium by the process of fusion. The mass defect in fusion reaction is 0.02866 u. The energy liberated per u is – (Given 1 u = 931 MeV)

asked Aug 20, 2018 by pady_1

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The half-life of a radioactive isotope ‘X’ is 20 years. It decays to another element ‘Y’ which is stable. The two elements ‘X’ and ‘Y’ were found to be in the ratio 1 : 7 in a sample of a given rock. The age of the rock is estimated to be -

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Ratio of longest wave lengths corresponding to Lyman and Balmer series in hydrogen spectrum is -

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The condition under which a microwave oven heats up a food item containing water molecules most efficiently is -

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A coil of self-inductance L is connected in series with a bulb B and an AC source. Brightness of the bulb decreases when -

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A wire loop is rotated in a magnetic field. The frequency of change of direction of the induced e.m.f. is -

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A bar magnet of length â€˜lâ€™ and magnetic dipole moment â€˜Mâ€™ is bent in the form of an arc as shown in figure. The new magnetic dipole moment will be â€“

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A current loop in a magnetic field -

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When a proton is released from rest in a room, it starts with an initial acceleration $a_0$ towards west. When it is projected towards north with a speed $v_0$ it moves with an initial acceleration $3a_0$ toward west. The electric and magnetic fields in the room are -

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The resistances of the four arms P, Q, R and S in a Wheatstone’s bridge are 10 ohm, 30 ohm, 30 ohm and 90 ohm, respectively. The e.m.f. and internal resistance of the cell are 7 volt and 5 ohm respectively. If the galvanometer resistance is 50 ohm, the current drawn from the cell will be -

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The internal resistance of a 2.1 V cell which gives a current of 0.2A through a resistance of $10 \Omega$ is -

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A wire of resistance 4Ω is stretched to twice its original length. The resistance of stretched wire would be -

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A, B and C are three points in a uniform electric field. The electric potential is -

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Two pith balls carrying equal charges are suspended from a common point by strings of equal length, the equilibrium separation between them is r. Now the strings are rigidly clamped at half the height. The equilibrium separation between the balls now become -

asked Aug 20, 2018 by pady_1

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A source of unknown frequency gives 4 beats/s, when sounded with a source of known frequency 250 Hz. The second harmonic of the source of unknown frequency gives five beats per second, when sounded with a source of frequency 513 Hz. The unknown frequency is -

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It we study the vibration of a pipe open at both ends, then the following statement is not true -

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