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प्रश्न
What is meant by radioactivity?
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उत्तर
Elements with a high atomic number such as uranium, thorium, radium have a property of spontaneously emitting invisible, highly penetrating and high energy radiation. This property is called radioactivity. The nucleus of radioactive elements is unstable.
संबंधित प्रश्न
What are free electrons?
Why do Free electrons not leave the metal surface on their own
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` ?
In a cathode ray tube state:
(i) the purpose of covering cathode by thorium and carbon.
(ii) the purpose of the fluorescent screen.
(iii) how is it possible to increase the rate of emission of electrons.
Give one example of isobars.
Define the term radioactivity.
Explain the use of radioactive in the field of medicine, agriculture and industry.
What are the uses of radioactive isotopes in following?
(a) Medical field,
(b) Agriculture,
(c) Industries?
What is nucleus of an atom? Compare its size with that of the atom. Name its constitutents. How is the number of these constituents determined by the atomic number its atomic model.
A radioactive source emits three types of radiations.
Name the radiation which has the highest ionizing power.
A certain nucleus A (mass number 238 and atomic number 92) is radioactive and becomes a nucleus B (mass number 234 and atomic number 90) by the loss of one particle.
What particle was emitted?
An element P disintegrates by α - -emission and the new element suffers two further disintegrations, both by β -emission, to form an element Q. Explain the fact that P and Q are the isotopes.
Why should a radioactive substance not be touched by hands?
State two characteristics of the substance used as thermionic emitter.
How is a cathode ray beam affected while passing through a magnetic field?
How is a zinc sulphide screen affected when a cathode ray beam strikes it?
In a cathode ray tube state. How is it possible to increase the rate of emission of electrons.
Name a common device where a hot cathode ray tube is used.
What is meant by Radioactivity?
From α, β and γ-rays, name the one which travels with the speed of light?
From α, β and γ-rays, name the one which is not affected by electric or magnetic field?
Unit of radioactivity is _______
Two radioactive sources A and B of half lives of 1 hour and 2 hours, respectively, initially contain the same number of radioactive atoms. At the end of two hours, their rates of disintegration are in the ratio of ______.
The activity of a certain radionuclide decreases to 15 percent of its original value in 10 days. What is its half life?
[ln (0.15) = -1.9]
If 10% of a radioactive substance decays in every 5 years, then the percentage of the substance that will have decayed in 20 years will be ______.
A radioctive sample decays `7/8` times its original quantity in 15 minutes. The half-life of the sample is ______.
Assertion (A): The force of repulsion between atomic nucleus and α-particle varies with distance according to inverse square law.
Reason (R): Rutherford did α-particles scattering experiment.
