Q.01

Identify the number of neutrons in a nucleus of polonium-210

(²¹⁰₈₄Po)

Explanation

A) 294
B) 210
C) 84
D) 126 √

Q.1(2).

A polonium-210 nucleus is formed when a stationary nucleus of bismuth-210 decays.
A beta-minus (β−) particle is emitted in this decay. Outline, with reference to β− decay, why bismuth-210 and polonium-210 have different proton numbers.

Explanation

• A neutron becomes a proton inside a nucleus during beta decay, which also results in the emission of a beta-minus () particle.
• One of the neutrons in bismuth-210 (Bi-210) undergoes decay, turning into a proton.
• A particle known as the one released during the decay process carries away the extra energy and charge created by the neutron-to-proton conversion.

• As a result, the nucleus’s proton count (atomic number) rises by
  one, resulting in the creation of polonium-210 (Po-210).
• Due to the decay process, which entails the conversion of a neutron
  into a proton and results in a rise in the atomic number of the nucleus,
  bismuth-210 and polonium-210 have distinct proton numbers.

Q.1(3) .

Figure 1 shows the variation with Ek of the number of β− particles that have
the kinetic energy Ek.

Explain how the data in Figure 1 support the hypothesis that a third particle is
produced during β− decay.

Explanation

• Figure 1 The 1.2 MeV total energy produced during the
  disintegration of bismuth-210 to polonium-210.
• We would expect to see a constant distribution of kinetic energy
  for these particles if only particles were emitted during the decay
  process. As seen in Figure 1, this would result in a smooth curve showing
  a continuous range of kinetic energy with no discernible characteristics.
• But above kinetic energy spectrum of the particles may show a
  clear energy gap or discontinuity in spectrum.

Q.1(4) .

Explanation

• β− decay involves the conversion of a neutron into a proton.
  The decay process is represented as: n → p + e− + ν̄e.
• Conservation laws dictate the production of an electron and an
  antineutrino.
• Lepton number must be conserved, resulting in the emission of an
  electron and an antineutrino.

• Neutrons and protons have a lepton number of 0.
• Electrons have a lepton number of +1, while antineutrinos have a lepton
  number of -1.
• 0 0 + (+1) + (-1)
• To conserve lepton number, an antineutrino is produced.
• Electric charge must also be conserved.
• Neutrons have a charge of 0, while protons have a charge of +1.
• An electron with a charge of -1 is emitted to maintain charge
  conservation.

Formation of Antineutrino from Beta Decay