(A) The position of an element in periodic table after emission of one `alpha` and two `beta`-partilce remians unchanged.
(R ) Emission of one `alpha` and two `beta` particles gives isotope of the parent element which acquires same position in the periodic table.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion
B. If both assertion and reason are true but reason is not the correct explanation of assertion
C. If assertion is true but reason is false
D. If both assertion and reason are false.

Answer

A

Explanation

The loss of one a-particle will reduce the mass number by four and atomic number by two. Subsequent two `beta`-emissions will inerease the atomic numbcr by two without affecting the mass number. Hence, the new element will be only an isotope of the parent nucleide and hence its position in the periodic table remains unchanged.