Question

A radioactive nucleus \({}_{92}X^{235}\) decays to \({}_{91}Y^{231}\). Which of the following particles are emitted?

• A. One alpha and one beta particle
• B. Two deuterons and one positron
• C. One alpha and one proton
• D. One proton and four neutrons

Hint:

Match the drop in mass number and atomic number with alpha and beta emissions.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept
An alpha particle lowers the mass number by 4 and the atomic number by 2. A beta particle (electron) leaves the mass number unchanged and raises the atomic number by 1.

Step 2: Mass number
The mass number falls from 235 to 231, a drop of 4. So exactly one alpha particle is emitted.

Step 3: Atomic number
One alpha lowers Z from 92 to 90. The final Z is 91, so Z must rise by 1, which needs one beta particle.

Final Answer:
One alpha particle and one beta particle are emitted. \[ \boxed{\text{(A) }\text{One alpha and one beta particle}} \]