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प्रश्न
Define the term radioactivity.
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उत्तर
The phenomenon of spontaneous disintegration of an unstable nucleus of a naturally occurring isotope accompanied by emission of active radiations, α particles, β particles and γ radiations is called radioactivity.
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संबंधित प्रश्न
Under which conditions does the nucleus of an atom tend to radioactive?
A nucleus `""_11^24Na` emits a beta particle to change into Magnesium (Mg)
(i) Write the symbolic equation for the process.
(ii) What are numbers 24 and 11 called?
(iii) What is the general name of `""_12^24Mg `with respect to `""_11^24Na` ?
What do you mean by Mass number.
What kind of change takes place in a nucleus when a β -particle is emitted?
A radioactive nuclide `""_86^226` Ra decays by emission of two alpha particles, one beta particle and gamma rays. Which of the following is the resulting nuclide X?
What do you mean by electron emission?
State two characteristics of the substance used as thermionic emitter.
State two properties that a substance should possess when used as a thermionic emitter.
What are cathode rays? Why are they called ‘cathode rays’? Name a material which exhibits fluorescence when cathode rays fall on it.
Which of the following statements is/are correct?
- α particles are photons
- Penetrating power of γ radiation is very low
- Ionization power is maximum for α rays
- Penetrating power of γ radiation is very high
