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Nuclei · Question 39

AIPMT 2010 (Prelims)MCQMedium📈 Topic in 25% papers+4−1
1

The activity of a radioactive sample is measured as N0 counts per minute at t = 0 and N0/e counts per minute at t = 5 minutes. The time (in minutes) at which the activity reduces to half its value is

  1. e 25
  2. 5 e 2
  3. 5 10 2
  4. 5 e 2

Answer

(4) 5 e 2

Solution

Activity: R = R0 e- t

N0e = N0 e-5

5 = 1, i.e. = 15 min-1

t1/2 = e 2

= 5 e 2 minutes

Answer: (4)

Out of syllabusAIPMT 2010 (Prelims)

Keep practising — Nuclei

2

In the nuclear decay given below AZX AZ+1Y A-4Z-1 B* A-4Z-1B, the particles emitted in the sequence are

  1. , ,
  2. , ,
  3. , ,
  4. , ,
Out of syllabusAIPMT 2009
3

The number of beta particles emitted by a radioactive substance is twice the number of alpha particles emitted by it. The resulting daughter is an

  1. isomer of parent
  2. isotone of parent
  3. isotope of parent
  4. isobar of parent
Out of syllabusAIPMT 2009
4

If M(A, Z), Mp and Mn denote the masses of the nucleus AZX, proton and neutron respectively in units of u (1 u = 931.5 MeV/c2) and BE represents its binding energy in MeV, then

  1. M(A, Z) = ZMp + (A - Z)Mn - BE
  2. M(A, Z) = ZMp + (A - Z)Mn + BE/c2
  3. M(A, Z) = ZMp + (A - Z)Mn - BE/c2
  4. M(A, Z) = ZMp + (A - Z)Mn + BE
AIPMT 2008
5

Two nuclei have their mass numbers in the ratio of 1 : 3. The ratio of their nuclear densities would be

  1. (3)1/3 : 1
  2. 1 : 1
  3. 1 : 3
  4. 3 : 1
Out of syllabusAIPMT 2008
6

Two radioactive materials X1 and X2 have decay constants 5 and respectively. If initially they have the same number of nuclei, then the ratio of the number of nuclei of X1 to that of X2 will be 1e after a time

  1. 14
  2. e
  3. 12
Out of syllabusAIPMT 2008
7

A nucleus AZX has mass represented by M(A, Z). If Mp and Mn denote the mass of proton and neutron respectively and B.E. the binding energy in MeV, then

  1. B.E. = [ZMp + (A - Z)Mn - M(A, Z)]c2
  2. B.E. = [ZMp + AMp - M(A, Z)]c2
  3. B.E. = M(A, Z) - ZMp - (A - Z)Mn
  4. B.E. = [M(A, Z) - ZMp - (A - Z)Mn]c2
AIPMT 2007
8

Two radioactive substances A and B have decay constants 5 and respectively. At t = 0 they have the same number of nuclei. The ratio of number of nuclei of A to those of B will be ( 1e )2 after a time interval

  1. 4
  2. 2
  3. 12
  4. 14
Out of syllabusAIPMT 2007
9

In a radioactive decay process, the negatively charged emitted -particles are

  1. the electrons produced as a result of the decay of neutrons inside the nucleus
  2. the electrons produced as a result of collisions between atoms
  3. the electrons orbiting around the nucleus
  4. the electrons present inside the nucleus
Out of syllabusAIPMT 2007
10

If the nucleus 2713Al has a nuclear radius of about 3.6 fm, then 12552Te would have its radius approximately as

  1. 9.6 fm
  2. 12.0 fm
  3. 4.8 fm
  4. 6.0 fm
Out of syllabusAIPMT 2007
11

The binding energy of deuteron is 2.2 MeV and that of 42He is 28 MeV. If two deuterons are fused to form one 42He then the energy released is

  1. 30.2 MeV
  2. 25.8 MeV
  3. 23.6 MeV
  4. 19.2 MeV
AIPMT 2006

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