1. A radioactive element emits an alpha particle. The mass number of the element , after emission ___________.
A. Remains unchanged
B. Increases by one
C. Increases by three
D. Decreases by four
ANSWER:D.Decreases by four
SOLUTION : When an alpha particle is emitted from a nucleus, the nucleus loses two protons and two neutrons. This means the mass number decreases by 4 and the atomic number decreases by 2. A new element is formed that is two places lower in the Periodic Table than the original element.
2. The velocity of neutron in a nuclear reactor is retarded by ________.
A. Ordinary water
B. Heavy water
C. Mercury
D. Alchohol
ANSWER:B.Heavy water
SOLUTION:Heavy water i.e., D2O slows down the speed of neutrons in nuclear reactors.
3. Gamma – ray photons have ___________.
A. No mass and no electric charge
B. No mass and an electric charge of +1
C. No mass and an electric charge of +2
D. No mass and an electric charge of -1
ANSWER : A.No mass and no electric charge
SOLUTION: Gamma-ray photons have the highest energy and shortest wavelength of any electromagnetic radiation (EMR) spectrum:
4. Natural radioactivity was discovered by _____.
A. Rutherford
B. Becquerel
C. Curie
D. Schmidt
ANSWER: B.Becquerel
SOLUTION:Henry Becquerel in 1896 discovered radioactivity proving that the uranium emitted radiation without an external source of energy such as the Sun. Uranium, Polonium is the radioactive element exhibit in nature.
5. A particle which is similar to electron is __________.
A. Positron
B. Beta particle
C. Photon
D. Mason
ANSWER: B.Beta particle
SOLUTION: The beta particle is similar to an electron because they have the same mass and charge. However, beta particles can have either a negative charge (negatrons) or a positive charge (positrons) and originate from the nucleus of an atom.
6. In Alpha Decay _____________.
A. Z and A are unchanged
B. Z decreases by 4 and A decreases by 2
C. Z decreases by 2 and A decrease by 4
D. Z decreases by 4 and A decreases by 4
ANSWER: C.Z decreases by 2 and A decrease by 4
SOLUTION: In alpha decay, the nucleus emits an alpha particle or a helium nucleus. Alpha decay occurs in massive nuclei that have a large proton to neutron ratio. Alpha radiation minimizes the protons to neutrons ratio in the parent nucleus, thereby bringing it to a more stable configuration.
7. A device used for the measurement of radioactivity is __________.
A. Mass spectrometer
B. Cyclotron
C. Nuclear reactor
D. G. M. counter
ANSWER: D. G. M. counter
SOLUTION :
The radioactivity is measured by the Geiger –Muller counter (G.M. Counter). The GM counter is used to detect the radioactive emission, most commonly for gamma and beta particles.
8. Hydrogen bomb is based on the principle of __________
A. Nuclear fission
B. Nuclear fusion
C. Natural radioactivity
D. Artificial radioactivity
ANSWER: B.Nuclear fusion
SOLUTION:A hydrogen bomb is based on the principle of uncontrollable nuclear fusion. Nuclear fusion is the process where the nuclei of two light atoms combine to form a new nucleus.
9. Phenomena of radioactivity was discovered by Henri Becquerel in ______________.
A. 1896
B. 1895
C. 1894
D. 1893
ANSWER:A.1896
SOLUTION:The phenomenon of radioactivity was discovered by Henry Becquerel in 1896.
10. Elements undergo radioactive decay when proton number becomes greater than _____________.
A. 50
B. 40
C. 82
D. 73
ANSWER: C.82
SOLUTION:
82