Concepts Of Physics MCQ Edition [Volume 2]PhysicsThe Nucleus
Lithium ( Z = 3 ) possesses two stable isotopes, ⁶ Li and ⁷ Li . When a lithium sample is bombarded with neutrons, electrons and -particles are ejected. Identify the correct set of nuclear processes taking place.
Options
- A⁶₃ Li + n ⁷₃ Li ⁷₃ Li + n ⁸₃ Li ⁸₄ Be + e⁻ + ⁸₄ Be ⁴₂ He + ⁴₂ He
- B⁶₃ Li + n ⁷₃ Li ⁷₃ Li + n ⁸₃ Li ⁸₄ Be + e⁻ + ⁸₄ Be ⁴₂ He + ⁴₁ H + n
- C⁶₃ Li + n ⁷₄ Be + e⁻ + ⁷₄ Be + n ⁸₄ Be ⁸₄ Be ⁴₂ He + ⁴₂ He
- D⁶₃ Li + n ⁷₃ Li ⁷₃ Li + n ⁸₃ Li ⁸₄ Be + e⁺ + ⁸₄ Be ⁴₂ He + ⁴₂ He
Correct answer
A. ⁶₃ Li + n ⁷₃ Li ⁷₃ Li + n ⁸₃ Li ⁸₄ Be + e⁻ + ⁸₄ Be ⁴₂ He + ⁴₂ He
Step-by-step solution
When a lithium sample containing ⁶₃ Li and ⁷₃ Li is bombarded with neutrons, the following nuclear reactions occur: First, ⁶₃ Li captures a neutron to form the stable isotope ⁷₃ Li : ⁶₃ Li + n ⁷₃ Li Next, ⁷₃ Li captures another neutron to form the radioactive isotope ⁸₃ Li : ⁷₃ Li + n ⁸₃ Li Since ⁸₃ Li has an excess of neutrons, it undergoes ⁻ decay to form ⁸₄ Be , emitting an electron ( e⁻ ) and an antineutrino ( ): ⁸₃ Li ⁸₄ Be + e⁻ + The resulting ⁸₄ Be nucleus is highly unstable and immediately fissions into two