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Nuclei · Question 34

AIPMT 2011 (Prelims)MCQEasy📈 Topic in 25% papers+4−1
1

The half life of a radioactive isotope X is 50 years. It decays to another element Y which is stable. The two elements X and Y were found to be in the ratio of 1 : 15 in a sample of a given rock. The age of the rock was estimated to be

  1. 150 years
  2. 200 years
  3. 250 years
  4. 100 years

Answer

(2) 200 years

Solution

NX : NY = 1 : 15

Initial amount of X: N0 = NX + NY = 16 parts

NN0 = 116 = ( 12 )4

Number of half lives = 4

t = 4 50 = 200 years

Answer: (2)

Out of syllabusAIPMT 2011 (Prelims)

Keep practising — Nuclei

2

A nucleus mnX emits one particle and two particles. The resulting nucleus is

  1. m-6n-4Z
  2. m-6nZ
  3. m-4nX
  4. m-4n-2Y
Out of syllabusAIPMT 2011 (Prelims)
3

The binding energy per nucleon in deuterium and helium nuclei are 1.1 MeV and 7.0 MeV, respectively. When two deuterium nuclei fuse to form a helium nucleus the energy released in the fusion is

  1. 23.6 MeV
  2. 2.2 MeV
  3. 28.0 MeV
  4. 30.2 MeV
AIPMT 2010 (Mains)
4

The decay constant of a radioisotope is . If A1 and A2 are its activities at times t1 and t2 respectively, the number of nuclei which have decayed during the time (t1 - t2)

  1. A1t1 - A2t2
  2. A1 - A2
  3. (A1 - A2)/
  4. (A1 - A2)
Out of syllabusAIPMT 2010 (Mains)
5

The mass of a 73Li nucleus is 0.042 u less than the sum of the masses of all its nucleons. The binding energy per nucleon of 73Li nucleus is nearly

  1. 46 MeV
  2. 5.6 MeV
  3. 3.9 MeV
  4. 23 MeV
AIPMT 2010 (Prelims)
6

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
Out of syllabusAIPMT 2010 (Prelims)
7

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
8

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
9

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
10

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
11

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
  4. 12
Out of syllabusAIPMT 2008

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