Recent questions tagged neet

Which of the following reactions is an example of nucleophilic substitution reaction ?

asked Jul 26, 2018 by pady_1

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Nitrobenzene can be prepared from benzene by using a mixture of conc.$ HNO_3$ and conc. $H_2SO_4$ . In the mixture, nitric acid acts as a/an -

asked Jul 26, 2018 by pady_1

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Benzene reacts with $CH_3 Cl $in the presence of anhydrous $AlCl_3$ to form -

asked Jul 26, 2018 by pady_1

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Consider the following reaction $Ethanol \xrightarrow{PBr_3} X \xrightarrow{ alc. KOH} Y \xrightarrow[{(i)\;H_2O ,\; Heat}]{(i)\; H_2SO_4 room\; temperature} Z$ The product Z is :

asked Jul 26, 2018 by pady_1

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Which of the following does not show optical isomerism - (en = Ethylenediamine)

asked Jul 26, 2018 by pady_1

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Out of $TiF_6^{2-}$and $CoF_6^{3-}$ , $Cu_2Cl_2$ and $NiCl_4^{2-}$ (Z of Ti = 22, Co = 27, Cu = 29, Ni = 28) the colourless species are : -

asked Jul 26, 2018 by pady_1

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Which of the following complex ions is expected to absorb visible light ? {At no. Zn = 30, Sc = 21, Ti = 22, Cr = 24)

asked Jul 26, 2018 by pady_1

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What is the dominant intermolecular force or bond that must be overcome in converting liquid $CH_3$ OH to a gas -

asked Jul 26, 2018 by pady_1

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Copper crystallizes in a face-centred cubic lattice with a unit cell length of 361 pm. What is the radius of copper atom in pm ?

asked Jul 26, 2018 by pady_1

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The stability of +1 oxidation state increases in the sequence :

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Half-life period of a first-order reaction is 1386 seconds. The specific rate constant of the reaction is :

asked Jul 26, 2018 by pady_1

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The values of $\Delta H$and $\Delta S$ for the reaction, $C(graphite)+CO_2(g)\rightarrow 2CO(g)$ are 170 kJ and $170 JK^{–1} $respectively. This reaction will be spontaneous at -

asked Jul 26, 2018 by pady_1

2 answers

The dissociation constants for acetic acid and HCN at 25ºC are $1.5\times10^5$ and $4.5\times10^{10}$, respectively. The equilibrium constant for the equilibrium - $CN^{-}+CH_3COOH\rightleftharpoons HCN+CH_3COO^{-}$ would be :

asked Jul 26, 2018 by pady_1

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Lithium metal crystallizes in a body centred cubic crystal. If the length of the side of the u cell of lithium is 351 pm, the atomic radius of lithium will be :

asked Jul 26, 2018 by pady_1

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In the reaction $BrO{_3}{^-}(aq)+5Br^-(aq)+6H^+\rightarrow 3Br_2(l)+3H_2O(l)$ The rate of appearance of bromine ($Br_2$ ) is related to rate of disappearance of bromide ions as following

asked Jul 26, 2018 by pady_1

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The energy absorbed by each molecule $ (A_2) $of a substance is $ 4.4 × 10^{–19 }J $ and bond energy per molecule is $ 4.0 × 10^{–19 }J $. The kinetic energy of the molecule per atom will be :

asked Jul 26, 2018 by pady_1

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What is the |$ [OH^-] $| in the final solution prepared by mixing 20.0 mL of 0.050 M HCl with 30.0 mL of 0.10 M $ Ba(OH)_{2}$ ? -

asked Jul 26, 2018 by pady_1

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Given : (i) $cu^{2+}+2e^{-}\to Cu,E^{\circ}=0.337 V$ (i) $cu^{2+}+e^{-}\to Cu,E^{\circ}=0.153V$ Electrode potential Eº for the reaction,$ Cu^{+} + e^{–}\rightarrow Cu$ will be :

asked Jul 26, 2018 by pady_1

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The ionization constant of ammonium hydroxide is $1.77\times10^{-5}$ at 298 K. Hydrolysis constant of ammonium chloride -

asked Jul 26, 2018 by pady_1

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From the following bond energies : H â€“ H bond energy : 431.37 kJ $mol^{â€“1}$ C = C bond energy : 606.10 kJ $mol^{â€“1}$ C â€“ C bond energy : 336.49 kJ $mol^{â€“1}$ C â€“ H bond energy : 410.50 kJ $mol^{â€“1}$ Enthalpy for the reaction,

asked Jul 26, 2018 by pady_1

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The symbolic representation of four logic gates are given below : The logic symbols for OR, NOT and NAND gates are respectively :

asked Jul 26, 2018 by pady_1

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A p–n photodiode is fabricated from a semiconductor with a band gap of 2.5 eV. It can detect a signal of wavelength :

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Sodium has body centred packing. Distance between two nearest atoms is 3.7 Å. The lattice parameter is :

asked Jul 26, 2018 by pady_1

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The mean free path of electrons in a metal is $4\times10^-8$ m. The electric field which can give on an average 2 eV energy to an electron in the metal will be in units of V/m :

asked Jul 26, 2018 by pady_1

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In the nuclear decay given below : The particles emitted in the sequence are :

asked Jul 26, 2018 by pady_1

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The figure shows a plot of photo current versus anode potential for a photo sensitive surface for three different radiations. Which one of the following is a correct statement ?

asked Jul 26, 2018 by pady_1

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Monochromatic light of wavelength 667 nm is produced by a helium neon laser. The power emitted is 9 mW. The number of photons arriving per second on the average at a target irradiated by this beam is :

asked Jul 26, 2018 by pady_1

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The number of photoelectrons emitted for light of a frequency v (higher than the threshold frequency $v_0$) is proportional to :

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If a diamagnetic substance is brought near the north or the south pole of a bar magnet, it is :

asked Jul 26, 2018 by pady_1

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A rectangular, a square, a circular and an elliptical loop, all in the (x – y) plane, are moving out of a uniform magnetic field with a r constant velocity, $\overrightarrow{V}=V.\widehat{i}$ . The magnetic field is directed along the negative z-axis direction. The induced emf, during the passage of these loops, come out of the field region, will not remain constant for :

asked Jul 26, 2018 by pady_1

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A galvanometer having a coil resistance of $60\Omega$ shows full scale deflection when a current of 1. amp passes through it. It can be converted into an ammeter to read currents upto 5.0 amp by :

asked Jul 26, 2018 by pady_1

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See the electrical circuit shown in this figure. Which of the following equations is a correct equation for it ?

asked Jul 26, 2018 by pady_1

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The electric potential at a point (x, y, z) is given by $V=-x^{2}y-xz^{3}+4$, The electric field E at that point is :

asked Jul 26, 2018 by pady_1

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A conducting circular loop is placed in a uniform magnetic field 0.04T with its plane perpendicular to the magnetic field. The radius of the loop starts shrinking at 2 mm/s. The induced emf in the loop when the redius is 2 cm is :

asked Jul 26, 2018 by pady_1

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A wave in a string has an amplitude of 2 cm. The wave travels in the +ve direction of x-axis with speed of 128 m/s and it is noted that 5 complete waves fit in 4 m length of the string. The equation describing the wave is

asked Jul 26, 2018 by pady_1

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The electric field part of an electromagnetic wave in a medium is represented by :$E_x=0$ $E_y=2.5\frac{N}{C}cos[(2\pi\times10^6\frac{rad}{m})t-(\pi\times10^{-2}\frac{rad}{s})x]$ $E_z=0$. The wave is :

asked Jul 26, 2018 by pady_1

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Which one of the following equations of motion represents simple harmonic motion ? Where $k,\; k_0,\; k_1$ and a are all positive

asked Jul 26, 2018 by pady_1

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A simple pendulum performs simple harmonic motion about x = 0 with an amplitude a and time period T. The speed of the pendulum at $x=a/2$will be :

asked Jul 26, 2018 by pady_1

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A body of mass 1 kg of thrown upwards with a velocity 20 m/s. It momenetarily comes to rest after attaining a height of 18m. How much energy is lost due to air friction ? $(g=10m/s^{2})$

asked Jul 26, 2018 by pady_1

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An engine pumps water continuously through a hose. Water leaves the hose with a velocity v an m is the mass per unit length of the water jet. What is the rate which kinetic energy is imparted to water ?

asked Jul 26, 2018 by pady_1

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The figure shows elliptical orbit of a planet m about the sun S. The shaded area SCD is twice the shaded are SAB. It $t_1$ is the time for the planet to move from C to D and $t_2$ is the time to move from A to B then

asked Jul 26, 2018 by pady_1

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If $\overrightarrow{F}$ is the force acting on a particle having position vector $\overrightarrow{r}$and $\overrightarrow{\tau}$ be the torque of this force about the origin, then :

asked Jul 26, 2018 by pady_1

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A body, under the action of a force $\overrightarrow{F}=6\widehat{i}-8\widehat{j}+10\widehat{k}$, acquires an acceleration of $1m/s^{2}$. The mass of this body must be :

asked Jul 26, 2018 by pady_1

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An explosion blows a rock into three parts Two parts go off at right angles to each other. These two are, 1 kg first part moving with a velocity of $12ms^{-1}$ and 2 kg second part moving with a velocity of $8ms^{-1}$ If the thirds part files off wi a velocity of $4ms^{-1}$, its mass would be :

asked Jul 26, 2018 by pady_1

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The mass of lift is 2000 kg. When the tension in the supporting cable is 28000 N, then its acceleration is :

asked Jul 26, 2018 by pady_1

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A bus is moving with a speed of $10ms^{-1}$ on a straight road. A scooterist wishes to overtake the bus in 100s. If the bus is at a distance of 1 from the scooterist, with what speed should the scooterist chase the bus ?

asked Jul 26, 2018 by pady_1

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A particle starts its motion from rest under the action of a constant force. If the distance covere in first 10 seconds is $S_1$ and that covered in the first 20 seconds is $S_2$ then :

asked Jul 26, 2018 by pady_1

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If the dimensions of a physical quantity are given by $[M^aL^bT^c]$, then the physical quantity will be:

asked Jul 26, 2018 by pady_1

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Which one of the following scientist's name is correctly matched with the theory put fourth by him? OPTIONS

asked Jul 26, 2018 by pady_1

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The fleshy receptacle of syconus of fig encloses a number of:

asked Jul 26, 2018 by pady_1

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