Biological importance of Ozone layer is
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(a) It stops ultraviolet rays |
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(b) Ozone rays reduce green house effect |
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(c) Ozone layer reflects radio waves |
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(d) Ozone layer controls |
(a) It stops ultraviolet rays
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Assertion : A metallic shield in form of a hollow shell may be built to block an electric field.
Reason : In a hollow spherical shield, the electric field inside it is zero at every point.
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(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
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(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
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(c) If assertion is true but reason is false. |
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(d) If the assertion and reason both are false. |
A soap bubble is given a negative charge, then its radius
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(a) Decreases |
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(b) Increases |
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(c) Remains unchanged |
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(d) Nothing can be predicted as information is insufficient |
The intensity of electric field required to balance a proton of mass 1.7 
and charge 1.6 
is nearly
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(a) |
(b) 1 |
(c) 1 |
(d) 1 |
A sky wave with a frequency 55 MHz is incident on D-region of earth's atmosphere at 45o. The angle of refraction is (electron density for D-region is 400 electron/cm3)
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(a) 60° |
(b) 45° |
(c) 30° |
(d) 15° |
In a Young's experiment, two coherent sources are placed 0.90 mm apart and the fringes are observed one metre away. If it produces the second dark fringe at a distance of 1 mm from the central fringe, the wavelength of monochromatic light used would be
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(a) 60 |
(b) 10 |
(c) 10 |
(d) 6 |
A proton, a deutron and an a-particle having the same momentum, enters a region of uniform electric field between the parallel plates of a capacitor. The electric field is perpendicular to the initial path of the particles. Then the ratio of deflections suffered by them is
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(a) 1 : 2 : 8 |
(b) 1 : 2 : 4 |
(c) 1 : 1 : 2 |
(d) None of these |
A resistor 
dissipates the power P when connected to a certain generator. If the resistor 
is put in series with , the power dissipated by
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(a) Decreases |
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(b) Increases |
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(c) Remains the same |
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(d) Any of the above depending upon the relative values of |
