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Nuclei · Question 33

AIPMT 2011 (Prelims)MCQEasy📈 Topic in 0% papers+4−1
1

Fusion reaction takes place at high temperature because

  1. nuclei break up at high temperature
  2. atoms get ionised at high temperature
  3. kinetic energy is high enough to overcome the Coulomb repulsion between nuclei
  4. molecules break up at high temperature

Answer

(3) kinetic energy is high enough to overcome the Coulomb repulsion between nuclei

Solution

As per NCERT, for fusion the two positively charged nuclei must come close enough for the short-range nuclear force to act, which requires overcoming the Coulomb barrier between them.

At very high temperatures, the nuclei acquire enough kinetic energy (thermal energy) to overcome this Coulomb repulsion; hence the process is called thermonuclear fusion.

Answer: (3)

AIPMT 2011 (Prelims)

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2

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
Out of syllabusAIPMT 2011 (Prelims)
3

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)
4

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)
5

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)
6

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)
7

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)
8

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
9

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
10

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
11

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

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