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Nuclei · Question 20

AIPMT 2015MCQEasy📈 Topic in 50% papers+4−1
1

A nucleus of uranium decays at rest into nuclei of thorium and helium. Then

  1. The helium nucleus has more momentum than the thorium nucleus.
  2. The helium nucleus has less kinetic energy than the thorium nucleus.
  3. The helium nucleus has more kinetic energy than the thorium nucleus.
  4. The helium nucleus has less momentum than the thorium nucleus.

Answer

(3) The helium nucleus has more kinetic energy than the thorium nucleus.

Solution

The uranium nucleus is at rest, by conservation of linear momentum:

pHe = pTh = p (equal and opposite)

Kinetic energy K = p22m ⇒ K 1m for equal momenta

mHe < mTh ⇒ KHe > KTh

The helium nucleus has more kinetic energy than the thorium nucleus.

Answer: (3)

AIPMT 2015

Keep practising — Nuclei

2

If radius of the 2713Al nucleus is taken to be RAl, then the radius of 12553Te nucleus is nearly

  1. 35 RAl
  2. ( 1353 )1/3 RAl
  3. ( 5313 )1/3 RAl
  4. 53 RAl
Out of syllabusAIPMT 2015 (Cancelled)
3

The binding energy per nucleon of 73Li and 42He nuclei are 5.60 MeV and 7.06 MeV respectively. In the nuclear reaction 73Li + 11H 42He + 42He + Q the value of energy Q released is

  1. 19.6 MeV
  2. -2.4 MeV
  3. 8.4 MeV
  4. 17.3 MeV
AIPMT 2014
4

A radioactive X with a half life 1.4 109 years decays to Y which is stable. A sample of the rock from a cave was found to contain X and Y in the ratio 1 : 7. The age of the rock is

  1. 1.96 109 years
  2. 3.92 109 years
  3. 4.20 109 years
  4. 8.40 109 years
Out of syllabusAIPMT 2014
5

A certain mass of Hydrogen is changed to Helium by the process of fusion. The mass defect in fusion reaction is 0.02866 u. The energy liberated per u is (given 1 u = 931 MeV)

  1. 6.675 MeV
  2. 13.35 MeV
  3. 2.67 MeV
  4. 26.7 MeV
NEET 2013
6

The half life of a radioactive isotope 'X' is 20 years. It decays to another element 'Y' which is stable. The two elements 'X' and 'Y' were found to be in the ratio 1 : 7 in a sample of a given rock. The age of the rock is estimated to be

  1. 80 years
  2. 100 years
  3. 40 years
  4. 60 years
Out of syllabusNEET 2013
7

How does the Binding Energy per nucleon vary with the increase in the number of nucleons ?

  1. Decreases continuously with mass number.
  2. First decreases and then increases with increase in mass number.
  3. First increases and then decreases with increase in mass number.
  4. Increases continuously with mass number.
NEET 2013 (Karnataka)
8

-particles, -particles and -rays are all having same energy. Their penetrating power in a given medium in increasing order will be

  1. , ,
  2. , ,
  3. , ,
  4. , ,
Out of syllabusNEET 2013 (Karnataka)
9

The half life of a radioactive nucleus is 50 days. The time interval (t2 - t1) between the time t2 when 23 of it has decayed and the time t1 when 13 of it had decayed is

  1. 30 days
  2. 50 days
  3. 60 days
  4. 15 days
Out of syllabusAIPMT 2012 (Mains)
10

If the nuclear radius of 27Al is 3.6 fermi, the approximate nuclear radius of 64Cu in fermi is

  1. 2.4
  2. 1.2
  3. 4.8
  4. 3.6
Out of syllabusAIPMT 2012 (Prelims)
11

A mixture consists of two radioactive materials A1 and A2 with half lives of 20 s and 10 s respectively. Initially the mixture has 40 g of A1 and 160 g of A2. The amount of the two in the mixture will become equal after

  1. 60 s
  2. 80 s
  3. 20 s
  4. 40 s
Out of syllabusAIPMT 2012 (Prelims)

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