A radioactive element X 92 242 emits two α -particles, one electron and two positrons. The product nucleus is represented by Y P 234 . The value of P is ______.

Step-by-step solution

When a radioactive nucleus emits 1   α -particle, its mass number decreases by 4 and the atomic number decreases by 2 . During positron emission, the mass number remains unchanged but the atomic number decreases by 1 . Similarly, during electron emission, the mass number remains unchanged but the atomic number decreases by 1 . So, the value of P = 92 - 2 - 2 + 1 - 1 - 1 ⇒ P = 92 - 5 ⇒ P = 87 .