3. Radioactivity

Q- Natural radioactivity was discovered by
(a) Rutherford (b) Becquerel
(c) Curie (d) Schmidt
Ans: (b)

Q- Isotopes of oxygen are
(a) 16O8 , 19O8 , 20O8
(b) 16O8 , 17O8 , 18O8
(c) 14O8 , 15O8 , 16O8
(d) 15O8 , 16O8 , 17O8
Ans: (b)

Q- One Curie of activity is equivalent to
(a) 3.7 × 1017 disintegration per second
(b) 3.7 × 1010 disintegration per second
(c) 3.7 × 1014 disintegration per second
(d) 3.7 × 103 disintegration per second
Ans: (b)

Q- The activity of radio-isotope change with
(a) temperature
(b) pressure
(c) chemical environment
(d) emmission of radiation
Ans: (d)

Q- Which one radiation has the highest energy?
(a) a-particles
(b) b-particles
(c) g-rays
(d) None of the above
Ans: (c)

Q- Which one of the following is not radioactive?
(a) Astatine (b) Francium
(c) Tritium (d) Zirconium
Ans: (d)

Q- Hydrogen bomb is based on the principle of
(a) nuclear fission
(b) nuclear fusion
(c) natural radioactivity
(d) artificial radioactivity
Ans: (b)

Q- The a-particles are
(a) high energy electrons
(b) positively charged hydrogen ions
(c) high energy X-ray radiations
(d) double positively charged helium nuclei
Ans: (d)

Q- Which of the following is a radioactive element?
(a) Sulphur (b) Polonium
(c) Tellurium (d) Selenium
Ans: (b)

Q- Match List-I with List-II and select the correct answer using the codes given below the lists: List-I (Characteristics) List-II (Particles)
A. Zero mass 1. Positron
B. Fractional charge 2. Neutrino
C. Fractional spin 3. Quark
D. Integral spin 4. Photon Codes A B C D
(a) 2 3 1 4
(b) 3 2 4 1
(c) 2 3 4 1
(d) 3 2 1 4
Ans: (a)

Q- In which process, a nucleus spontaneously breaks down by emitting radiation?
(a) Radioactive decay
(b) Fusion
(c) Refraction
(d) None of the above
Ans: (a)

Q- Emission of b-particle from an atom
(a) increases the number of protons in the atom
(b) increases the number of neutrons in the atom
(c) decreases the number of proton in the atom
(d) does not change the number of neutrons and protons in an atom
Ans: (a)

Q- The fuel in atomic pile is
(a) carbon (b) sodium
(c) petroleum (d) uranium
Ans: (d)

Q- Match the List-I and List-II and select the correct answer using the codes given below the lists: List-I (Nuclear reactor component) List-II (Substance used)
A. Moderator 1. Uranium
B. Control rod 2. Graphite
C. Fuel rods 3. Boron
D. Coolant 4. Sodium Codes A B C D
(a) 2 1 3 4
(b) 2 3 1 4
(c) 3 2 1 4
(d) 3 4 1 2
Ans: (b)

Q- In atomic reactors, graphite is used as
(a) lubricant
(b) fuel
(c) linear of the reactor
(d) moderator
Ans: (d)

Q- Energy produced in nuclear reaction is given by
(a) Charle’s law
(b) Graham’s law
(c) Gay-Lussac’s law
(d) Einstein’s law
Ans: (d)

Q- Cobalt-60 is commonly used in radiation therapy because it emits
(a) a-rays
(b) b-rays
(c) gamma rays
(d) X-rays
Ans: (c)

Q- Match the list-I (Radio-isotope) with list-II (Medicinal use) and select the correct matching: List-I List-II
A. 60CO 1. Leucaemia
B. 131I 2. Anaemia
C. 59Fe 3. Cancerous tumours
D. 32P 4. Disorders of thyroid gland Codes A B C D
(a) 3 4 1 2
(b) 1 2 3 4
(c) 3 4 2 1
(d) 4 3 2 1
Ans: (c)

Q- Which one of the following can be used to confirm whether drinking water contains a gamma emitting isotope or not?
(a) Microscope
(b) Lead plate
(c) Scintillation counter
(d) Spectrophotometer
Ans: (c)

Q- A radioactive substance has a halflife of four months. Three-fourth of the substance would decay in
(a) 3 months (b) 4 months
(c) 8 months (d) 12 months
Ans: (c)

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