Question

In the given radioactive decay if the mass number and atomic number of D2 are 176 and 71 respectively.What is the mass number and atomic number of D? D----->D1------->D2 Bita alpha particle

Answer 1

Well,though not clearly mentioned,considering,the reaction to be,

`D ------> D_1 + beta ------> D_2+alpha`

Given, mass number of `D_2` is `176`, now as `D_2` has been formed from `D_1` due to `alpha` emission,mass number of `D_1` must be `(176+4)-180` and similarly atomic number should be `71+2=73` (as, alpha particle has mass number `4` and atomic number `2`)

So, we can complete the `2nd` half of the reaction,

`""_73^180 D_2 -------> ""_71^176 D_3 + ""_2^4 He`

Similarly, we can say, there will be no change in mass number of `D` as,beta particle has mass number of `0` as beta emission is expressed as, `""_(-1)^ 0 beta`,So its atomic number must decrease by `1` i.e `72`

So,the whole reaction becomes,

`""_72^180 D ---->""_73^180 D_2 + ""_-1^0 beta -------> ""_71^176 D_3 + ""_2^4 He`