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1. When
7 3 Li are bombarded with protons, (^) -rays
are produced. The nuclide formed is [CPMT 1987]
(a)
8 3 Li (b)
8 4 Be
(c)
9 3 B (d)
9 4
Be
2. Nuclides [BVP 2003]
(a) Have specific atomic numbers
(b) Have same number of protons
(c) Have specific atomic number and mass
numbers
(d) Are isotopes
3. In the following nuclear reactions
1
17 8
4 2
14 7 N^ He O X^ and 2
28 14
2 1
27 13 Al^ D Si X
X 1 and X 2 are respectively [MP PMT 1999]
(a)
1 1 H and
1 0 n (b)
1 0 n and
1 1 H
(c)
4 2 He and
1 0 n (d)
1 0 n and
4 2 He
4. Gamma rays are
[NCERT 1978; MNR 1990; UPSEAT 1999, 2000]
(a) High energy electromagnetic waves
(b) High energy electrons
(c) High energy protons
(d) Low energy electrons
5. Which particle can be used to change
27 13 Al into
30 15
P
[MP PMT 2003]
(a) Neutron (b) -particle
(c) Proton (d) Deuteron
6. Which of the following does not characterise X -
rays
[UPSEAT 2001]
(a) The radiation can ionise gases
(b) It causes ZnS to fluorescence
(c) Deflected by electric and magnetic field
(d) Have wavelengths shorter than ultraviolet
rays
7. During emission of -particle [Bihar MEE 1996]
(a) One electron increases
(b) One electron decreases
(c) One proton increases
(d) No change
(e) None of these
8. Emission is caused by the transformation of one
neutron into a proton. This results in the
formation of a new element having
(a) Same nuclear charge
(b) Very lower nuclear charge
(c) Nuclear charge higher by one unit
(d) Nuclear charge lower by one unit
9. The end product of 4 n series is [MNR 1983]
(a)
208 82 Pb (b)
207 82 Pb
(c)
209 82 Pb (d)
204 83 Bi
235 (^) 92 U belongs to group III B of periodic table. If
it loses one -particle, the new element will
belong to group
[MNR 1984; CPMT 2001]
(a) I B (b) I A
(c) III B (d) V B
11. Radioactive disintegration differs from a chemical
change in being [UPSEAT 2000, 01, 02]
(a) An exothermic change
(b) A spontaneous process
(c) A nuclear process
(d) A unimolecular first order reaction
12. Half-life is the time in which 50% of radioactive
element disintegrates. Carbon- 14 disintegrates
50% in 5770 years. Find the half-life of carbon- 14 [DPMT 1996]
(a) 5770 years
(b) 11540 years
(c) 5770 years
(d) None of the above
13. The half-life of C
14 is about [MP PET 1996]
(a) 12.3 years
(b) 5730 years
(c)
9
- 5 10 years
(d)
5
- 52 10 years
14. Half-life for radioactive
14 C is 5760 years. In how
many years (^200) mg of
14 C sample will be reduced
to 25 mg
[CBSE PMT 1995]
(a) 11520 years (b) 23040 years
(c) 5760 years (d) 17280 years
15. The decay constant of a radioactive element is
6 1 3 10 min
. Its half-life is
[MP PET 1993; Pb. CET 2002]
(a) 2. 31 10 min
5
(b) 2. 31 10 min
6
(c) 2. 31 10 min
6
(d) 2. 31 10 min
7
16. A radioactive sample decays to half of its initial
concentration in 6.93 minutes .It further decays
half in next 6.93 minutes. The rate constant for
the reaction is
[RPET 2000]
(a) 0.10 min
(c) 1.0 min
- 1 (d) 0.001 min - 1 17. The half-life of an isotope is 10 hrs. How much
will be left behind after 4 hrs in 1 gm sample [BHU 1997]
(a)
23
- 6 10 atoms
(b)
23
- 56 10 atoms
(c)
21
- 56 10 atoms
(d)
21 45.^6 ^10 atoms
18. The half-life period t 1 / 2 of a radioactive element
is N years. The period of its complete decay is [KCET 1998]
(a)
2 N years (b) 2 N years
(c)
2
2
1 N years (d) Infinity
19. A radioactive element has a half-life of 20
minutes. How much time should elaspe before the
element is reduced to th 8
1 of the original mass [EAMCET 1990]
(a) 40 minutes
(b) 60 minutes
(c) 80 minutes
(d) 160 minutes
20. The half-life period of a radioactive material is 15
minutes. What % of radioactivity of that material
will remain after 45 minutes [MP
(a) 10 % (b) 12.5%
(c) 15% (d) 17.5%
21. Ra
226 disintegrates at such a rate that after 3160
years only one-fourth of its original amount remains.
The half-life of Ra
226 will be [MP PET 200
(a) 790 years (b) 3160 years
(c) 1580 years (d) 6230 years
22. The ratio of the amount of two elements X and Y
at radioactive equilibrium is
6 1 : 2 10
. If the half-
life period of element Y is
4
- 9 10
days, then the
half-life period of element X will be
(a)
3
- 8 10
days (b) 245 days
(c) 122.5 days (d) None of these
23. If half-life of a substance is 5 yrs , then the total
amount of substance left after 15 years , when
initial amount is 64 grams is [AIEEE 2002]
(a) 16 grams (b) 2 grams
(c) 32 grams (d) 8 grams
24. An element has half-life 1600 years. The mass left
after 6400 years will be [AFMC 2003]
(a) 1/16 (b) 1/
(c) 1/4 (d) 1/
25. Wooden artitact and freshly cut tree are 7.6 and
1 1
- 2 min
g of carbon ( 5760 t 1 / 2 years)
respectively. The age of the artitact is [AIIMS 1980]
(a) 576 0 years
(b)
6
2 5760 years
(c)
2
6 5760 years
(d) 5760 (^15.^2 ^7.^6 )years
26. An element has two main isotopes of mass
numbers 85 and 87. In nature they occur in the
ratio of 75% and 25% respectively. The atomic
weight of the element will be approximately
(a) 86.0 (b) 86.
(c) 85.5 (d) 85.
27. A sample of rock from moon contains equal
number of atoms of uranium and lead ( t 1 / 2 for
9 U 4. 5 10 years). The age of the rock would be [MNR 1988; UPSEAT 20
(a)
9
- 0 10 years
25. (a) ro 15. 2 and r 7. 6 , r
r t
o log
- 303
26. (c) Isotopes have 75% and 25% respectively.
Atomic mass =
27. (b) n
N N 2
0 , use N
t N t
o log
693
303 1 / 2
28. (c) 1 Ci = dps
10
- 7 10 or 3. 7 10.
10 Bq
1 mCi = dps
4
- 7 10.
29. (d) Tritium ( )
3 1 H consist of 1 proton and 2
neutrons.
