Emission of one α-particle from a nucleus results the loss of two protons and two neutrons from the — Nuclear Chemistry and Radioactivity Chemistry Question

💡 Solution & Explanation

Step 1 - Stability of Helium-4 Cluster The alpha particle (2p+2n) has binding energy ~28.3 MeV, making it a highly stable pre-formed cluster inside the parent nucleus. Step 2 - Quantum Tunneling Mechanism The pre-formed cluster escapes the parent nucleus via quantum barrier tunneling as a single unified entity: \ce{^A_Z X -> ^{A-4}_{Z-2}Y + ^4_2He^{2+}} Breaking the cluster sequentially would require 28.3 MeV input — energetically impossible for spontaneous decay. Step 3 - All particles exit simultaneously oxed{A}