Question

Assertion (A) : All the radioactive elements are ultimately converted into lead
Reason (R): All the elements above lead are unstable

• A. Both A and R are true and R is correct explanation of A
• B. Both A and R are true and R is not correct explanation of A
• C. A is true but R is false
• D. A is false but R is true

Answer 1

The correct option is D A is false but R is true

For all $4n,4n+2$ series elements, on emission of different kind of rays, they form different isotopes of lead and also all element above lead are unstable .
But, $4n+1$ series elements (Neptunium series), end in ${}_{83}^{209}Bi$ (Bismuth not lead)