Recent questions tagged 2014

In acidic medium, $H_2O_2$ changes $Cr_2 O_7^{-2}$ to $CrO_5$ which has two $(- O - O - )$ bonds Oxidation state of $Cr$ in $CrO_5$ is :

asked Aug 20, 2018 by pady_1

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Artificial sweetner which is stable under cold conditions only is :

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(a) $H_2O_2 + O_3 \to H_2O + 2O_2$ (b) $H_2O_2 + Ag_2O \to 2Ag +H_2O + O_2$ Role of hydrogen peroxide in the above reactions is respectively :

asked Aug 20, 2018 by pady_1

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Acidity of diprotic acids in aqueous solutions increases in the order:

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Which one of the following species has plane triangular shape?

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Which of the following molecules has the maximum dipole moment?

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$Be^{2+}$ is isoelectronic with which of the following ions?

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The pair of compounds that can exist together is:

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1.0 g of magnesium is burnt with 0.56 g $O_2$ in a closed vessel. Which reaction is left in excess and how much? (At, wt.Mg = 24; O = 16)

asked Aug 20, 2018 by pady_1

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Which of the following orders of ionic radii is correctly represented?

asked Aug 20, 2018 by pady_1

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For a given exothermic reaction, $K_P$ and $K_P'$ are the equilibrium constants at temperatures $T_1$ and $T_2$ respectively. Assuming that heat of reaction is constant in temperatures range between $T_1$ and $T_2$ , it is readily observation that:

asked Aug 20, 2018 by pady_1

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For the reaction : $X_2O_4 (l) \to 2XO_2 (g)$ $\Delta U = 2.1 \; k \; cal, \; \Delta s = 20 \; cal \; K^{-1} $ at $300 K$

asked Aug 20, 2018 by pady_1

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For the reversible reaction : $N_2 (g) + 3H_2(g) \leftrightharpoons 2NH_3 (g) + heat$ The equilibrium shifts in forward direction -

asked Aug 20, 2018 by pady_1

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Which of the following statements is correct for the spontaneous adsorption of a gas?

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The weight of silver (at.wt. = 108) displaced by a quantity of electricity which displaces 5600 ml of $O_2$ at STP will be -

asked Aug 20, 2018 by pady_1

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Using the Gibbs change, $\Delta G^o = + 63.3 \;kJ$, for the following reaction, $Ag_2CO_3 (g) \leftrightharpoons 2 Ag^+ (aq) + CO^{2-}_3 (aq)$ the $K_{sp}$ of $Ag_2CO_3 (s)$ in water at $25^oC$ is ($R = 8.314 \; JK^{-1} mol^{-1}$)

asked Aug 20, 2018 by pady_1

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When 0.1 mol $MnO_4^{2-}$ is oxidised the quantity of electricity required to completely $MnO_4^{2-}$ to $MnO_4^-$ is -

asked Aug 20, 2018 by pady_1

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When 22.4 litres of $H_2(g) $ is mixed with 11.2 litres of $Cl_2 (g)$, each at STP, the moles of $HCl(g) $ formed is equal to -

asked Aug 20, 2018 by pady_1

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Of the following 0.1 M aqueous solutions, which one will exhibit the largest freezing point depression ?

asked Aug 20, 2018 by pady_1

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Which of the following salts will give highest pH in water?

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Which property of colloids is not dependent on the charge on colloidal particles?

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If a the length of the side of a cube, the distance between the body centered atom one corner atom in the cube will be -

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Equal masses of $H_2, O_2$ and methane have been taken in a container of volume V at temperature $27^oC$ in identical conditions. The ratio of the volumes of gases $H_2: O_2: methane$ would be -

asked Aug 20, 2018 by pady_1

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Calculate the energy in corresponding to light of wavelength 45nm : (Planck's constant $h = 6.63 \times 10^{-34} Js$ : speed of light $c = 3 \times 10^8 ms^{-1}$)

asked Aug 20, 2018 by pady_1

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What is the maximum number of orbitals that can be identified with the following quantum number n = 3, $\ell$ = 1, m = 0

asked Aug 20, 2018 by pady_1

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The barrier potential of a p-n junction depends on : (a) type of semi conductor material (b) amount of doping (c) temperature Which one of the following is correct?

asked Aug 20, 2018 by pady_1

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The given graph represents V-I characteristic for a semiconductor device. Which of the following statement is correct?

asked Aug 20, 2018 by pady_1

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A radio isotope 'X' with a half life $1.4 \times 10^9$ years decays to 'Y' which is stable. A sample of the rock from a cave was found to contain 'X' and 'Y' in the ratio 1 : 7. The age of the rock is :

asked Aug 20, 2018 by pady_1

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The Binding energy per nucleon of $_3^7Li$ and $_2^4 He$ nucleon are 5.60 MeV and 7.06 MeV, respectively. In the nuclear reaction $_3^7Li + _1^1 He \to _2^4 He + _2^4 He + Q, $ the value of energy $Q$ released is :

asked Aug 20, 2018 by pady_1

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Hydrogen atom in ground state is excited by a monochromatic radiation of $\lambda= 975 A^o$. Number of spectral lines in the resulting spectrum emitted will be :

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If the kinetic energy of the particle is increased to 16 times its previous value, the percentage change in the de-Broglie wavelength of the particle is:

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When the energy of the incident radiation is increased by $20%$, the kinetic energy of the photoelectrons emitted from a metal surface increased from emitted 0.5 eV to 0.8eV. The work function of the metal is :

asked Aug 20, 2018 by pady_1

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The angle of a prism is 'A'. One of its refracting surfaces is silvered. Light rays falling at an angle of incidence 2A on the first surface returns back through the same path after suffering reflection at the silvered surface. The refractive index $\mu$, of the prism is:

asked Aug 20, 2018 by pady_1

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It the focal length of objective lens is increased then magnifying power of:

asked Aug 20, 2018 by pady_1

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In the Young's double slit experiment the intensity of light at a point on the screen where the path difference is $\lambda$ is K, ($\lambda$ being the wave length of light used). The intensity at a point where the path difference is $\lambda/4$, will be :

asked Aug 20, 2018 by pady_1

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A beam of light of $\lambda$ = 600 nm from a distant source falls on a single slit 1 mm wide and the resulting diffraction pattern is observed on a screen 2m away. The distance between first dark fringes on either side of the central bright fringe is :

asked Aug 20, 2018 by pady_1

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Light with an energy flux of $25 \times 10^4\; wm^{-2}$ falls on a perfectly reflecting surface at normal incidence. If the surface area is $15\; cm^2$ , the average force exerted on the surface is:

asked Aug 20, 2018 by pady_1

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A transformer having efficiency of 90% is working on 200 V and 3 kW power supply. If the current in the secondary coil is 6 A the voltage across the secondary coil and the current in the primary coil respectively are:

asked Aug 20, 2018 by pady_1

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A thin semicircular conducting the ring (PQR) of radius 'r' is falling with its plane vertical in a horizontal magnetic field B, as shown in figure. Teh potential difference developed across the ring when its speed is v, is:

asked Aug 20, 2018 by pady_1

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Two identical long conducting wires AOB and COD are placed at right angle to each other, with one above other such that $'O'$ is their common point for the two. The wires carry $I_1$ and $I_2$ currents, respectively. Point 'I' is lying at distance 'd' from '$O$' along a direction perpendicular to the plane containing the wires. The magnetic field at the point 'P' will be :

asked Aug 20, 2018 by pady_1

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In an ammeter 0.2% of main current passes through the galvanometer. If resistance of galvanometer is G, the resistance of ammeter will be:

asked Aug 20, 2018 by pady_1

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Following figures show the arrangement of bar magnets in different configurations. Each magnet has magnetic dipole $\overrightarrow{m}$ . Which configuration has highest net magnetic dipole moment?

asked Aug 20, 2018 by pady_1

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A potentiometer circuit has been set up for finding the internal resistance of a given cell. The main battery, used across the potentiometer wire, has an emf of 2.0 V and a negligible internal resistance. The potentiometer wire itself is 4 m long. When the resistance, R, connected acrose the given cell, has values of. (i) infinity $\; \; \; \; \; \; $ (ii) 9.5 Q The 'balancing lengths, on the potentiometer wire are found to be 3m and 2.85 m, respectively. The value of internal resistance of the cell is:

asked Aug 20, 2018 by pady_1

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The resistance in the two arms of the meter bridge are 5 $\Omega$ and R $\Omega$ , respectively. When the resistance R is shunted with an equal resistance, the new balance point is at $1.6 \ell_1$ . The resistance 'R' is :

asked Aug 20, 2018 by pady_1

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Two cities are 150 km apart. Electric power is sent from one city to another city through copper wires. The fall of potential per km is 8 volt and the average resistance per km is 0.5 $\Omega$ The power loss in the wire is:

asked Aug 20, 2018 by pady_1

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In a region the potential is represented by V(x, y, z) = 6x - 8xy - 8y + 6yz, where Vis in volts and x, y, z, are in meters. The electric force experienced by a charge of 2 coulomb situated at point (1, 1,1) is :

asked Aug 20, 2018 by pady_1

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A conducting sphere of radius R is given a charge Q. The electric potential and the electric field at the centre of the sphere respectively are:

asked Aug 20, 2018 by pady_1

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Two thin dielectric slabs of dielectric constants $K_1$ and $K_2 ( K_1 < K_2)$ are inserted between plates of a parallel plate capacitor, as shown in the figure. The variation of electric field 'E' between the plates with distance 'd' as measured from plate P is correctly shown by:

asked Aug 20, 2018 by pady_1

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A speeding motorcyclist sees traffic jam ahead of him. He slows down to 36km/hour. He finds that traffic has eased and a car moving ahead of him at 18 km/hour is honking at a frequency of 1392 Hz. If the speed of sound is 343 m/s, the frequency of the honk as heard by him will be:

asked Aug 20, 2018 by pady_1

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The number of possible natural oscillations of air column in a pipe closed at one end of length 85 cm whose frequencies lies below 1250 Hz are: (velocity of sound = $340 \;ms^{-1}$)

asked Aug 20, 2018 by pady_1

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