An element `A` decays into element `C` by a two-step process :
`A rarr B + ._2 He^4`
`B rarr C + 2 e overline`
Then.

Options

A. A and B are isobars
B. A and C are isotopes
C. A and C are isobars
D. A and B are isotopes

Answer

B

Explanation

Element A emits an a particle `(""_2He^4)` and is converted into element B.
`therefore` Charge of A decreases by 2 and the mass number of A decreases by 4. .
`therefore` If Z is the atomic number of A, then for B, it is Z-2 and for Cit is Z-2+2 = Z. For B mass number is A-4 and for C it is not changed. Thus A and C have the same atomic number (Z) but different mass numbers A and A-4.
`therefore` A and C are isotopes .