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Question Bank No: 1

1. After 2hr the radioactive substance becomes $\frac{1}{16 th}$ of original amount. The $t_{\frac{1}{2}}$ in minutes is

a)		60 min
b)		120 min
c)		30 min
d)		15 min

2. The symbol $χ$ in the following equation is
$11^{{Na}^{23}}$ $+ 1^{H^{1}}$ $\to 12^{{Mg}^{23}} + χ$

a)		A neutron
b)		A deutron
c)		A positron
d)		An $α$ - particle

3. The end product of (4n + 2) disintegration series is

a)		${}_{82}^{204}{Pb}$
b)		${}_{82}^{208}{Pb}$
c)		${}_{82}^{209}{Pb}$
d)		${}_{82}^{206}{Pb}$

4. ${}_{92}^{235}U$ $+ n \to$ ${}_{92}^{235}{U \to}$ Fission product $+$ neutron $+$ 19.293 $\times 10^{9}$ kJ . The energy released when 1 g of ${}_{92}^{235}U$ undergoes fission is

a)		12.75 $\times 10^{8}$ kJ
b)		18.6 $\times 10^{9}$ kJ
c)		8.21 $\times 10^{7}$ kJ
d)		6.55 $\times 10^{6}$ kJ

5. In a nuclear reactor, the function of moderator is

a)		to slow down the speed of neutron
b)		to increase the speed of neutron
c)		to produce more neutrons
d)		to stop the nuclear reaction

6. After emission of one $α$ particle followed by one $β -$ particle from ${}_{92}^{238}\times$ the number of neutrons in the atom will be

a)		142
b)		146
c)		144
d)		143

7. In radioactive transformation
${}_{92}{U^{238}} \to {}_{82}{{Pb}^{206},}$ the number of $α$ and $β$ particles emitted are

a)		10 $α$ , 6 $β$
b)		4 protons , 8 neutrons
c)		6 electrons , 8 protons
d)		6 $β, 8 α$

8. Half life of radioactive substance is 60 min. During 3 hrs, the fraction of total no.of atoms that have decayed would be

a)		12.5%
b)		87.5%
c)		8.5%
d)		25%

9. In radioactive decay, the emitted electrons come from

a)		nucleus of the atom
b)		the orbital with principal quantum number 1
c)		inner orbital of atoms
d)		the outermost shell of atom

10. A radioactive sample has half life of 1500 years. Ascaled tube containing 1 g of a sample will be containing...... of the sample after 3000 years. The missing figure is

a)		1 g
b)		0.5g
c)		0.25g
d)		0g

11. If amount of radioactive substance is increased three times, the number of disintegrating atoms per unit time will be

a)		doubled
b)		tripled
c)		one third
d)		unchanged

12. Insert the missing figure in the following ${}_{25}^{55}{Mn (n, y) \to}$

a)		${}_{25}^{56}{Mn}$
b)		${}_{24}^{55}{Cr}$
c)		${}_{25}^{55}{Mn}$
d)		${}_{24}^{56}{Cr}$

13. The change ${}_{15}^{30}{P \to {}_{14}^{30}{Si}}$ requires the emission of

a)		$α$ - particle
b)		$β -$ particle
c)		neutron
d)		positron

14. The reaction
${}_{1}^{2}{D + {}_{1}^{3}{T \to {}_{2}^{4}{He + {}_{0}^{1}n}}}$
is an example of

a)		Nuclear fission
b)		Nuclear fusion
c)		Artificial radioactivity
d)		Radioactive disintegration

15. Which of the following does not contain material particles ?

a)		$α$ -rays
b)		$β$ - rays
c)		anode rays
d)		$γ$ - rays

16. Group displacement law was given by

a)		Becquerel
b)		Rutherford
c)		Mendeleef
d)		Soddy and Fazan

17. If 2.0g of a radioactive substance has $t_{1 / 2}$ of 7 days, the half life of 1g sample is

a)		7 days
b)		14 days
c)		28 days
d)		35 days

18. $β$ - particle are

a)		charged particles emitted from nucleus
b)		neutral particles orbiting nucleus
c)		a particle produced by splitting of $α$ into $H^{\circ}$ and $n_{0}^{1}$
d)		high energy positively charged particles emitted from nucleus

19. The radioactive isotop used to estimate the age of ancient geological formations is

a)		$O^{16}$
b)		${Pb}^{212}$
c)		${Fe}^{59}$
d)		$C^{14}$

20. If ${}_{90}{Th}^{228}$ disintegrates to ${}_{83}{Bi}^{212}$ then the number of $α$ and $β$ particles emitted is

a)		4 $α$ and 7 $β$
b)		4 $α$ and 1 $β$
c)		4 $α$ only
d)		7 $β$ only

21. Which does not take place by $α$ - disintegration?

a)		${{}_{92}U}^{238} \to {{}_{90}U}^{234}$
b)		${}_{90}{Th}^{232} \to {}_{88}{Ra}^{228}$
c)		${}_{88}{Ra}^{226} \to {}_{86}{Rn}^{222}$
d)		${}_{83}{Bi}^{213} \to {}_{84}{Po}^{213}$

22. Which of the following is used as control rod?

a)		Cadmium rod
b)		Graphite rod
c)		Boron
d)		Both (A) & �

23. Which of the following is (n, p) type reaction?

a)		${{}_{5}C}^{13} + {{}_{1}H}^{1} \to {{}_{6}C}^{14}$
b)		${{}_{7}N}^{14} + {{}_{1}H}^{1} \to {{}_{8}O}^{15}$
c)		${}_{13}{Al}^{27} + {{}_{0}n}^{1} \to {}_{12}{Mg}^{27} + {{}_{1}H}^{1}$
d)		${{}_{92}U}^{235} + {{}_{0}n}^{1} \to {}_{54}{Xe}^{140} + {}_{88}{Sr}^{94}$

24. Which of the following statements is wrong?

a)		$P^{33}$ is used in the treatment of Leukemia
b)		$I^{131}$ is used in the treatment of Thyroid Gland Cancer
c)		${Co}^{59}$ can't be used for treatment of Cancer
d)		Excessive use of radioactive elements is responsible for cancerous growth

25. In a reaction, ${}_{3}^{7}{Li + Z \to {}_{4}^{7}{Be} + {}_{0}^{1}n}$ the bombarding projectile Z is

a)		$α$ - particle
b)		Deutron
c)		Neutron
d)		Proton

26. Which of the following elements belongs to 4n-series?

a)		Pb-206
b)		Bi-209
c)		Pb-208
d)		Pb-207

27. The equipment used to carry out nuclear reaction in a controlled manner is called

a)		Breedor reactor
b)		Nuclear reactor
c)		Thermonuclear fission
d)		Cyclotron

28. A radioactive isotop decays at such a rate that after 96min. Only 1/8th of the original amount remains. The value of $t_{1 / 2}$ of this nuclide is

a)		12.0 min
b)		32.0 min
c)		24.0 min
d)		48.0 min

29. C-14 has a half life of 5760 years. 100 mg of sample containing C-14 is reduced 25mg in

a)		11,520 yrs
b)		2880 yrs
c)		1440 yrs
d)		17280 yrs

30. Starting from radium, the radioactive disintegration process terminates when the following is obtained

a)		lead
b)		radon
c)		radium A
d)		radium B

31. When ${{}_{92}U}^{235}$ nuclide is bombarded with slow neutrons, the uranium nuclide undergoes

a)		fusion
b)		fission
c)		radioactive decay
d)		no change