Question

Which one of the options is correct about \( \beta^- \) decay?

• A. Atomic number increases and mass number remains constant
• B. Atomic weight increases and atomic number remains constant
• C. Number of protons increases and number of neutrons remains constant
• D. Number of neutrons increases and number of protons remains constant

Hint:

In \( \beta^- \) decay: neutron \( \rightarrow \) proton + electron + antineutrino. Hence, atomic number increases, but mass number remains the same.

Answer 1

The Correct Option is A

Step 1: Understanding \( \beta^- \) decay. 
In \( \beta^- \) decay, a neutron in the nucleus converts into a proton and emits an electron (beta particle) and an antineutrino. 
Step 2: Effect on atomic number and mass number. 
The proton count increases by 1, so the atomic number increases. The total nucleons (protons + neutrons), i.e., the mass number, remains unchanged.