Question

What missing item would complete this alpha decay -----228/88Ra + 4/2He

Answer 1

²³²₉₀Th ---> ²²⁸₈₈Ra + ⁴₂He

Answer 2

Answer : The complete alpha decay reaction will be,

`_(292)^(90)\textrm{Th}\rightarrow _(88)^(288)\textrm{Ra}+_2^4He`

Explanation :

Alpha decay : In this process, alpha particles is emitted when a heavier nuclei decays into lighter nuclei. The alpha particle released has a charge of +2 units.

The general representation of alpha decay reaction is:

`_Z^A\textrm{X}\rightarrow _(Z-2)^(A-4)Y+_2^4\alpha`

From the given reaction we conclude that,

`Z-2=88\\\\Z=88+2=90\\\\A-4=288\\\\A=288+4=292`

So, the element is thorium that has atomic number 90 and atomic mass 292.

The complete alpha decay reaction will be,

`_(292)^(90)\textrm{Th}\rightarrow _(88)^(288)\textrm{Ra}+_2^4He`