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In the Bohr model of the hydrogen atom, the lowest orbit corresponds to
A 2μ F capacitor is charged to 100 volt and then its plates are connected by a conducting wire. The heat produced is
The force experienced by the cathode rays when they pass through an electric field of intensity E → is
A steady current of 1.5 A flows through a copper voltameter for 10 min. If the electrochemical equivalent of copper is 30x10-5 g C-1 , the mass of copper deposited on the electrode will be
If sky wave with a frequency of 50 MHz is incident on D-region at an angle of 30o, then angle of refraction is
Two wires of the same metal have same length, but their cross-sectional areas are in the ratio 3 : 1. If resistance of the thicker wire is 10 Ω, then total resistance of the wires in series combination will be
The number of dry cells, each of e.m.f. 1.5 volt and internal resistance 0.5 ohm that must be joined in series with a resistance of 20 ohm so as to send a current of 0.6 ampere through the circuit is
Two cells of the same emf are in series with an external resistance R. The internal resistance r1 is greater than r2. The p.d across the first cell is found to be zero. Then the value of R is
On increaing the number of electrons striking the anode of an X-ray tube, which one of the following parameters of the resulting X-ray would increase
A 50 ohm galvanometer gets full scale deflection when a current of 0.01 A passes through the coil. When it is converted to a 10 A ammeter, the shunt resistance is
Energy needed to establish an alternating current I in a coil of self inductance L is
E = 1/2 LI2
When current cahnge from + 2 A to -2 A in 0.05 s, an e.m.f. of 8 V is induced in a coil. The coefficient of self inductance of the coil is
Which one of the following electromagnetic radiations have the smallest wavelength?
A sphere S1 of radius r1 encloses a total charge Q. If there is another concentric sphere S1 of radius r2 > r1 and there be no additional charges between S1 and S2, the ratio of electric flux through S1 and S2 is
On moving a charge of 20 C by 2 cm, 2 joule of work is done, then the potential difference between the points is
W = QV
∴ V = W/Q = 2/20 = 0.1 volt
A hollow metal sphere of radious 10 cm is charged such that the potential on its surface is 80V. The potential at the centre of the sphere is
The capacitor of a parallel plate capacitor with no dielectric substance and a separation of 0.4 cm is 2 μF. The separation is reduced to half and it is filled with a substance of dielectric value 2.8. The new capacity of the capacitor is
A conducting sphere of radius 10 cm is charged with 10 μC. Another uncharged sphere of radius 20 cm in allowed to touch it for some time. If both the spheres are separated, then surface density of charges on the spheres will be in the ratio of
The capacity of a condenser 'A' is 10 μ F and it is charged by a battery of 100V. The battery is disconnected and the condenser is connected to a condenser 'B'. The common potential is 40V. The capacity of 'B' is
The magnetic field near a current carrying conductor is given by
What is the particle x in the following nuclear reaction?
Two radioactive substances A and B have decay constants 5 λ and λ respectively. At t = 0 they have the same number of nuclei. The ratio of number of nuclei of A to those of B will be (1/e)2 after a time interval
Which of the following is not dependent on the intensity of incident radiation in a photoelectric experiment ?
Green light of wavelength 5460 Å is incident on an air glass interface. If refractive index of glass is 1.5, then wavelength of light in glass would be
The work function of oxide coated tungsten emitter will be
If a battery is connected across a p - n junction with the p - type to the negative terminal, the junction is said to be
The angle of a prism is 600 and the angle of minimum deviation of light passing through it is observed to be 400. The angle of incidence of light is
The most commonly used material for making transistor is
Which of the following statement is true about p-type semiconductors?
If the phase differenc between light waves from two slits of Young's double slit experiment is π radian, then the central fringe will be
When distance between source of light and observer decreases, then the apparent frequency of light
In young's double slit experiment, the intensity of central maximum is I. It one slit is closed, the intensity at the same place will become
Two waves of same frequency, but of amplitudes in the ratio 1:3 are superimposed. The ratio of maximum to minimum intensity is
Which one of the following will produce a primary alcohol by reacting with CH₃MgI?
Which of the following will respond to Cannizzaro's reaction
The cyanohydrin of a compound X on hydrolysis gives lactic acid; The X is
Which of the following does not turn Schiff's reagent to pink ?
How many monochlorobutanes will be obtained on chlorination of n-butane?
The reaction CH₃CH₂Br + OH- → CH₃CH₂OH + Br- is an example of;
The reason for double helical structure of DNA is operation of
An alkyl cyanide forms an amide when it is treated with
In a reaction involving ring substitution of C6H5Y, the major product is meta isomer. The group Y can be
Electron withdrawing groups favour meta substitution
- COOH group is metadirecting group
when a catalyst is added to a reversible reaction in equilibrium state, the value of equilibrium constant
The reaction N₂ + O₂ → 2NO is endothermic . The forward reaction is
Latent heat of vaporisation of a liquid at 500 K and 1 atm pressure is 10.0 kcal/mol. What will be the change in internal energy (ΔE) of 3 mol of liquid at same temperature?
Vaporization of 3 moles of H2O vapors is:
3H2O(l) → 3H2O(g)
Δn = 3 - 0 = 3
ΔU = ΔH - ΔnRT
= (3 x 10) - 3 (0.002) (500) = 27
change in internal energy is:
ΔU = 27 Kcal
The densities of graphite and diamond at 298 K are 2.25 and 3.31 g-cm-3 respectively. If the standard free energy difference (ΔGo)is equal to 1895 J-mol-1, then pressure at which graphite will be transformed into diamond at 298 K is
The heat of neutralisation is maximum when
The heat of neutralisation of any strong acid (HCl, HNO3, H2SO4) with a strong base (LiOH, NaOH, KOH) is always maximum (57.1 kJ). In case, either the acid or the base or both are weak, the heat of neutralisationis usually less than 57.1 kJ.
Which of the following compounds shows optical isomerism?
In the electrolysis of dilute H₂SO₄ using platinum electrode
The indicator that is obtained by coupling the diazonium salt of sulphanilic acid with N,N-dimethylaniline is
If specific conductance and conductance of a solution is same, then its cell constant is equal to
The e.m.f. of a galvanic cell with electrode potentials of Al equal to -1.66 V and that of Mg equal to - 0.54 V is
E.M.F. can be positive only if oxidation takes place at Mg-electrode. But here the reduction reaction takes place.
A real gas most closely approaches the behaviour of an ideal gas at
Which one of the following compounds does not exist ?
Acetic anhydride reacts with diethyl ether in the presence of anhydrous AlCl₃ to give
Which one of the following elements is most metallic?
Fill in the blank with appropriate word.
The problems suggested by style as a sign and index of personality may be......from many points of view.
Out of the given alternatives, choose the one which can be substituted for the given capitalised word.
There is NO LOVE LOST between the two neighbours.
Improve the sentence by choosing best alternative for capitalised part of the sentence.
Books for the used-book sales should be in good condition AND SHOULD HAVE NO WRITING IN THEM OR BE UNDERLINED.