1. : Which scientist discovered radioactivity?
(A) J.J. Thomson
(B) Madame Curie
(C) Henry Becquerel
(D) Rutherford
2. : Have same atomic numbers but different atomic masses
(A) Isotope
(B) Atom
(C) Radioisotope
(D) None of these
3. : When a radioactive substance is subjected to a vacuum, the rate of disintegration per second
(A) Increases only if the products are gaseous
(B) Increase considerably
(C) Decreases
(D) Is not affected
4. : Radioactive has an unstable nucleus and undergoes radioactive decay.
(A) Isotope
(B) Atom
(C) Radioisotope
(D) None of these
5. : Which one of the following are Gamma rays?
(A) Low energy waves
(B) High energy protons
(C) High energy electron
(D) High energy electromagnetic waves
6. : Which one of the following has no charge?
(A) Gamma rays
(B) Beta rays
(C) Alpha rays
(D) Cathode rays
7. : Which of the following is the smallest particle of an element that retains the properties of that element?
(A) Isotope
(B) Atom
(C) Radioisotope
(D) None of these
8. : Hydrogen bomb is based on the phenomenon of
(A) Nuclear explosion
(B) Chemical reaction
(C) Nuclear fusion
(D) Nuclear fission
9. : Which of the following does uranium give as a stable isotope?
(A) Radon
(B) Krypton
(C) Polonium
(D) Radium
10. : Penetrating power of proton is
(A) Greater than electron
(B) Lesser than electron
(C) Greater than neutron
(D) None
11. : The average life period of a radioactive element is
(A) 1.44 T
(B) 144 T
(C) 0.144 T
(D) 14.4 T
12. : A certain nuclide has a half-life period of 30 minutes. If a sample containing 600 atoms is allowed to decay for 90 minutes, how many atoms will remain?
(A) 175 atoms
(B) 250 atoms
(C) 450 atoms
(D) 75 atoms