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Nuclei · Question 54

AIPMT 2005MCQEasy📈 Topic in 0% papers+4−1
1

Fission of nuclei is possible because the binding energy per nucleon in them

  1. increases with mass number at low mass numbers
  2. decreases with mass number at low mass numbers
  3. increases with mass number at high mass numbers
  4. decreases with mass number at high mass numbers.

Answer

(4) decreases with mass number at high mass numbers.

Solution

As per NCERT, the binding energy per nucleon curve rises to a maximum (about 8.75 MeV near A = 56) and then decreases slowly for heavier nuclei (about 7.6 MeV for A = 238).

When a heavy nucleus (high A) breaks into two middle-mass nuclei, the binding energy per nucleon increases and energy is released.

Fission is possible because the binding energy per nucleon decreases with mass number at high mass numbers.

Answer: (4)

AIPMT 2005

Keep practising — Nuclei

2

Which one of the following pairs of nuclei are isotones ?

  1. 34Se74, 31Ga71
  2. 38Sr84, 38Sr86
  3. 42Mo92, 40Zr92
  4. 20Ca40, 16S32
Out of syllabusAIPMT 2005
3

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 2004
4

If in a nuclear fusion process the masses of the fusing nuclei be m1 and m2 and the mass of the resultant nucleus be m3, then

  1. m3 = m1 + m2
  2. m3 = |m1 - m2|
  3. m3 < (m1 + m2)
  4. m3 > (m1 + m2)
AIPMT 2004
5

A nucleus represented by the symbol AZX has

  1. Z neutrons and A - Z protons
  2. Z protons and A - Z neutrons
  3. Z protons and A neutrons
  4. A protons and Z - A neutrons
Out of syllabusAIPMT 2004
6

The half life of radium is about 1600 years. Of 100 g of radium existing now, 25 g will remain unchanged after

  1. 4800 years
  2. 6400 years
  3. 2400 years
  4. 3200 years
Out of syllabusAIPMT 2004
7

Solar energy is mainly caused due to

  1. burning of hydrogen in the oxygen
  2. fission of uranium present in the Sun
  3. fusion of protons during synthesis of heavier elements
  4. gravitational contraction
AIPMT 2003
8

The volume occupied by an atom is greater than the volume of the nucleus by a factor of about

  1. 101
  2. 105
  3. 1010
  4. 1015
AIPMT 2003
9

The mass of proton is 1.0073 u and that of neutron is 1.0087 u (u = atomic mass unit). The binding energy of 42He is (Given helium nucleus mass ≈ 4.0015 u.)

  1. 0.0305 J
  2. 0.0305 erg
  3. 28.4 MeV
  4. 0.061 u
AIPMT 2003
10

A sample of radioactive element has a mass of 10 g at an instant t = 0. The approximate mass of this element in the sample after two mean lives is

  1. 1.35 g
  2. 2.50 g
  3. 3.70 g
  4. 6.30 g
Out of syllabusAIPMT 2003
11

The mass number of a nucleus is

  1. always less than its atomic number
  2. always more than its atomic number
  3. sometimes equal to its atomic number
  4. sometimes less than and sometimes more than its atomic number
Out of syllabusAIPMT 2003

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