Respuesta :

This is alpha decay not beta decay. 

Fermium 257 decays by ALPHA decay into 253 Cf which has an atomic number of 98 

So your reaction is 

257Fm --> 253Cf...+ 4He 
100................98.........2 


Interestingly Californium does undergo beta decay. 

253Cf ---> 253Es + e- 
98...............99 

Hope this helps.

From the question,

Fermium which atomic mass of 257 decay through alpha to 253 Cf

The reaction is stated below.

257Fm --> 253Cf...+ 4He

100 98 2

Therefore,

253Cf ---> 253Es + e-

98 . 99

What is Alpha decay?

Alpha decay is a form of radioactive decay that occur in the nucleus of an atom and the atomic nucleus emits an alpha particle which them decays into another atomic nucleus, with different mass number that is reduced by four.

Therefore, the completed part is

253Cf ---> 253Es + e-

98 . 99

Learn more about alpha decay below.

https://brainly.com/question/17796856

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