Question

Assertion : The position of an element in periodic table after emission of after α, and two β-particles remains unchanged. 

Reason: Emission of one o and two β-particles give isotope of the clement which acquires same position in periodic table.

(a) Both A and R are true and R is the correct explanation of A  

(b) Both A and R are true but R is not correct explanation of A  

(c) A is true but R is false  

(d) A and R are false

Answer 1

Correct option (a) Both A and R are true and R is the correct explanation of A  

Explanation:

The loss of one α-particle will reduce the mass number by four and atomic number by two. Subsequent two β-emissions will increase the atomic number by two without affecting the mass number. Hence, the new element will be only an isotope of the parent nuclide and hence its position in the periodic table remains unchanged.