- AContinuous
- ✓Line spectrum
- CSpectrum of black lines
- DSpectrum of black bonds
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The half life of radioactive Radon is 3.8 days. The time at the end of which 1/20 th of the Radon sample will remain undecayed is (Given ![]()
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(a) 3.8 days |
(b) 16.5 days |
(c) 33 days |
(d) 76 days |
An oxide coated filament is useful in vacuum tubes because essentially
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(a) It has high melting point |
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(b) It can withstand high temperatures |
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(c) It has good machanical strength |
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(d) It can emit electrons at relatively lower temperatures |
The maximum wavelength of radiation that can produce photoelectric effect in a certain metal is 200 nm. The maximum kinetic energy acquired by electron due to radiation of wavelength 100 nm will be
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(a) 12.4 eV |
(b) 6.2 eV |
(c) 100 eV |
(d) 200 eV |
Two resistors having equal resistances are joined in series and a current is passed through the combination. Neglect any variation in resistance as the temperature changes. In a given time interval
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(a) Equal amounts of thermal energy must be produced in the resistors |
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(b) Unequal amounts of thermal energy may be produced |
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(c) The temperature must rise equally in the resistors |
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(d) The temperature must rise unequally in the resistors |
A metallic loop is placed in a magnetic field. If a current is passed through it, then
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(a) The ring will feel a force of attraction |
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(b) The ring will feel a force of repulsion |
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(c) It will move to and fro about its centre of gravity |
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(d) None of these |
de-Broglie wavelength of a body of mass 1 kg moving with velocity of 2000 m/s is
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(a) 3.32 × 10–27 Å |
(b) 1.5 × 107 Å |
(c) 0.55 × 10–22 Å |
(d) None of these |