A hydrogen atom (ionisation potential 13.6 eV) makes a transition from third excited state to first excited state. The energy of the photon emitted in the process is
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(a) 1.89 eV |
(b) 2.55 eV |
(c) 12.09 eV |
(d) 12.75 eV |
(b) 2.55 eV
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In case of a real and inverted image, the magnification created by the mirror is:
Assertion : Free electron always keep on moving in a conductor even then no magnetic force act on them in magnetic field unless a current is passed through it.
Reason : The average velocity of free electron is zero.
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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. |
What fraction of a radioactive material will get disintegrated in a period of two half-lives
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(a) Whole |
(b) Half |
(c) One-fourth |
(d) Three-fourth |
Given a point source of light, which of the following can produce a parallel beam of light
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(a) Convex mirror |
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(b) Concave mirror |
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(c) Concave lens |
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(d) Two plane mirrors inclined at an angle of 90° |