Step 1: Effect of Alpha ( ) Decay
An alpha particle () has a mass number of 4 and an atomic number of 2.
When element undergoes alpha decay:
Thus, the new nucleus has:
Mass number =
Atomic number =
Step 2: Effect of Positron () Emission
Positron emission () decreases the atomic number by 1 without changing the mass number:
Thus, has:
Mass number = 286 (unchanged)
Atomic number =
Step 3: Effect of Beta-Minus () Decay
Beta-minus () emission increases the atomic number by 1 without affecting the mass number:
Thus, has:
Mass number = 286 (unchanged)
Atomic number =
Step 4: Effect of Electron Capture ()
Electron capture decreases the atomic number by 1, keeping the mass number unchanged:
Thus, has:
Mass number = 286 (unchanged)
Atomic number =
Conclusion
The final product has mass number 286 and atomic number 81, which corresponds to option (4).
Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A : The potential (V) at any axial point, at 2 m distance(r) from the centre of the dipole of dipole moment vector
of magnitude, 4 × 10-6 C m, is ± 9 × 103 V.
(Take SI units)
Reason R : , where r is the distance of any axial point, situated at 2 m from the centre of the dipole.
In the light of the above statements, choose the correct answer from the options given below :