A nucleus of Uranium-238 undergoes alpha decay. What is the mass number of the resulting nucleus?
Q1. A nucleus of Uranium-238 undergoes alpha decay. What is the mass number of the resulting nucleus?
Answer: 234
Explanation: Alpha decay reduces mass number by 4. Resulting nucleus has mass number 238 - 4 = 234. Option 'B' incorrectly adds 2 protons.