Recent questions tagged 2013

Experimentally it was found that a metal oxide has formula $M_{0.98}O$. Metal M, is present as $M^{2+}$and $M^{3+}$ in its oxide. Fraction of the metal which exists as $M^{3+}$ would be :

asked Apr 7, 2017 by meena.p

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The gas leaked from a storage tank of the Union Carbide plant in Bhopal gas tragedy was :

asked Apr 7, 2017 by meena.p

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An unknown alcohol is treated with the “Lucas reagent” to determine whether the alcohol is primary, secondary or tertiary. Which alcohol reacts fastest and by what mechanism :

asked Apr 7, 2017 by meena.p

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Stability of the species $Li_2 , Li^{-}_2$ and $Li^{+}_{2}$ increases in the order of

asked Apr 7, 2017 by meena.p

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An organic compound A upon reacting with $NH_3$ gives $B$.On heating, B gives $C$.$C$ in presence of $KOH$ reacts with $Br_2$ to give $CH_3CH_2NH_2.A$ is :

asked Apr 7, 2017 by meena.p

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The first ionisation potential of $Na$ is $5.1\;eV$. The value of electron gain enthalpy of $Na^+$ will be :

asked Apr 7, 2017 by meena.p

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How many litres of water must be added to 1 litre of an aqueous solution of HCl with a pH of 1 to create an aqueous solution with $pH$ of $2$ ?

asked Apr 6, 2017 by meena.p

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Four successive members of the first row transition elements are listed below with atomic numbers. Which one of them is expected to have the highest $E^0_{M^{3+} /m^{2+}}$ value ?

asked Apr 6, 2017 by meena.p

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Compound (A), $C_8H_9Br$, gives a white precipitate when warmed with alcoholic $AgNO_3$.Oxidation of (A) gives an acid (B) , $C_8H_6O_4$ . (B) easily forms anhydride on heating. Identify the compound (A) .

asked Apr 6, 2017 by meena.p

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Energy of an electron is given by $E= -2.178 \times 10^{18} J \bigg(\large\frac{Z^2}{n^2}\bigg)$. Wavelength of light required to excite an electron in an hydrogen atom from level $n = 1$ to $n = 2$ will be

asked Apr 6, 2017 by meena.p

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Which of the following represents the correct order of increasing first ionization enthalpy for $Ca, Ba, S, Se \;and\; Ar ?$

asked Apr 6, 2017 by meena.p

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The coagulating power of electrolytes having ions $Na^{+} ,Al^{3+}$ and $Ba^{2+}$ for arsenic sulphide sol increases in the order :

asked Apr 6, 2017 by meena.p

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Synthesis of each molecule of glucose in photosynthesis involves :

asked Apr 6, 2017 by meena.p

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Which of the following exists as covalent crystals in the solid state ?

asked Apr 5, 2017 by meena.p

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In which of the following pairs of molecules / ions , both the species are not likely to exist ?

asked Apr 5, 2017 by meena.p

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A gaseous hydrocarbon gives upon combustion $0.72\; g$. of water and $3.08\;g$ of $CO_2$. The empirical formula of the hydrocarbon is :

asked Apr 5, 2017 by meena.p

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Which of the following is the wrong statement ?

asked Apr 5, 2017 by meena.p

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Consider the following reaction : $xMnO_4^{-} +yC_2O_4^{2-} +zH^{+} \to xMn^{2+} +2yCO_2 +\large\frac{z}{2}$$H_2O$The values of x, y and z in the reaction are, respectively :

asked Apr 5, 2017 by meena.p

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The order of stability of the following carbocations is:

asked Apr 5, 2017 by meena.p

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Which of the following arrangements does not represent the correct order of the property stated against it ?

asked Apr 4, 2017 by meena.p

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A compound with molecular mass $180$ is acylated with $CH_3COCl$ to get a compound with molecular mass 390. The number of amino groups present per molecule of the former compound is :

asked Apr 4, 2017 by meena.p

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The rate of a reaction doubles when its temperature changes from $300 \;K$ to $310\; K$. Activation of such a reaction will be :

asked Apr 4, 2017 by meena.p

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For a gaseous state, if most probable speed is denoted by $C^{*}$ , average speed by C and mean square speed by C, then for a large number of molecules the ratios of these speeds are :

asked Apr 4, 2017 by meena.p

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Arrange the following compounds in order of decreasing acidity :

asked Apr 4, 2017 by meena.p

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The molarity of a solution obtained by mixing $750\; mL$ of $0.5\;(M)HCl$ with $250\; mL$ of $2(M)HCl$ will be :

asked Apr 4, 2017 by meena.p

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A piston filled with $0.04\; mol$ of an ideal gas expands reversibly from $50.0 \;mL$ to $375\;mL$ at a constant temperature of $37.0^{\circ} C$. As it does so, it absorbs $208\; J$ of heat. The values of q and w for the process will be

asked Apr 4, 2017 by meena.p

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Given : $E^0_{Cr^{3+}/Cr} =-0.74\;V ; E^0_{MnO^{-}_4/Mn^{2+}}=1.51\;V $$E^0_{Cr_2O^{2-}_7/Cr^{3+}} =-1.33\;V ; E^0_{Cl/Cl^{-}}=1.36\;V $ Based on the data given above, strongest oxidising agent will be :

asked Apr 4, 2017 by meena.p

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A solution of $(−)−1− chloro − 1− phenylethane$ in toluene racemises slowly in the presence of a small amount of $SbCl_5$ ,due to the formation of :

asked Apr 4, 2017 by meena.p

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Which one of the following molecules is expected to exhibit diamagnetic behaviour ?

asked Apr 4, 2017 by meena.p

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Which of the following complex species is not expected to exhibit optical isomerism ?

asked Apr 4, 2017 by meena.p

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A charge Q is uniformly distributed over a long rod AB of length L as shown in the figure. The electric potential at the point O lying at a distance L from the end A is :

asked Apr 3, 2017 by meena.p

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Two short bar magnets of length 1 cm each have magnetic moments $1.20\; Am^2$ and $1.00 Am^2$ respectively. They are placed on a horizontal table parallel to each other with their N poles pointing towards the South. They have a common magnetic equator and are separated by a distance of $20.0\; cm$. The value of the resultant horizontal magnetic induction at the mid - point O of the line joining their centre is close to (Horizontal component of earth′s magnetic induction is $3.6 \times 10^{−5} Wb / m^2)$

asked Apr 3, 2017 by meena.p

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Two charges, each equal to q, are kept at $x = − a$ and $x = a$ on the x−axis. A particle of mass $m$ and charge $q_0 = \large\frac{q}{2}$ is placed at the origin. If charge $q_0$ is given a small displacement $(y << a)$along the y−axis, the net force acting on the particle is proportional to :

asked Apr 3, 2017 by meena.p

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The graph between angle of deviation $(\delta)$ and angle of incidence (i) for a triangular prism is represented by :

asked Apr 3, 2017 by meena.p

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In a hydrogen like atom electron makes transition from an energy level with quantum number $n$ to another with quantum number $(n − 1).$ If $n >> 1$, the frequency of radiation emitted is proportional to :

asked Apr 3, 2017 by meena.p

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Assume that a drop of liquid evaporates by decrease in its surface energy. So that its temperature remains unchanged. What should be the minimum radius of the drop for this to be possible? The surface tension is $T$, density of liquid is $\rho$ and $L$ is its latent heat of vaporization.

asked Apr 3, 2017 by meena.p

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The I − V characteristic of an LED is :

asked Apr 3, 2017 by meena.p

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The anode voltage of a photocell is kept fixed. The wavelength λ of the light falling on the cathode is gradually changed. The plate current I of the photocell varies as follows :

asked Apr 3, 2017 by meena.p

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The magnetic field in a travelling electromagnetic wave has a peak value of $20\;nT$. The peak value of electric field strength is :

asked Apr 3, 2017 by meena.p

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Two coherent point sources $S_1$ and $S_2$ are separated by a small distance 'd' as shown. The fringes obtained on the screen will be :

asked Mar 30, 2017 by meena.p

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In an LCR circuit as shown below both switches are open initially. Now switch $S_1$ is closed, $S_2$ kept open. (q is charge on the capacitor and $\tau = RC$ is Capacitive time constant). Which of the following statement is correct?

asked Mar 30, 2017 by meena.p

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This question has statement I and Statement II. Of the four choices given after the Statements, choose the one that best describes the two statements. <br>Statement − I : Higher the range, greater is the resistance of ammeter. <br> Statement − II : To increase the range of ammeter, additional shunt needs to be used across it.

asked Mar 30, 2017 by meena.p

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If a piece of metal is heated to temperature $\theta$ and then allowed to cool in a room which is at temperature $\theta_0$, the graph between the temperature $T$ of the metal and time $t$ will be closed to :

asked Mar 30, 2017 by meena.p

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An ideal gas enclosed in a vertical cylindrical container supports a freely moving piston of mass M. The piston and the cylinder have equal cross sectional area A. When the piston is in equilibrium, the volume of the gas is $V_0$ and its pressure is $P_0$. The piston is slightly displaced from the equilibrium position and released. Assuming that the system is completely isolated from its surrounding, the piston executes a simple harmonic motion with frequency :

asked Mar 29, 2017 by meena.p

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A hoop of radius r and mass m rotating with an angular velocity $\omega$ is placed on a rough horizontal surface. The initial velocity of the centre of the hoop is zero. What will be the velocity of the centre of the hoop when it ceases to slip ?

asked Mar 29, 2017 by meena.p

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The above p-v diagram represents the thermodynamic cycle of an engine, operating with an ideal monoatomic gas. The amount of heat, extracted from the source in a single cycle is :

asked Mar 29, 2017 by meena.p

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The supply voltage to a room is $120\; V$. The resistance of the lead wires is $6 \Omega$ . A $60\;W$ bulb is already switched on. What is the decrease of voltage across the bulb, when a $240\; W$ heater is switched on in parallel to the bulb?

asked Mar 29, 2017 by meena.p

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A beam of unpolarised light of intensity $I_0$ is passed through a polaroid $A$ and then through another polaroid $B$ which is oriented so that its principal plane makes an angle of $45^{\circ}$ relative to that of A. The intensity of the emergent light is :

asked Mar 29, 2017 by meena.p

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A diode detector is used to detect an amplitude modulated wave of $60\%$ modulation by using a condenser of capacity $250$ pico farad in parallel with a load resistance 100 kilo ohm. Find the maximum modulated frequency which could be detected

asked Mar 28, 2017 by meena.p

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What is the minimum energy required to launch a satellite of mass $m$ from the surface of a planet of mass $M$ and radius $R$ in a circular orbit at an altitude of $2R$ ?

asked Mar 28, 2017 by meena.p

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