Answer:
This is an example of alpha decay
Step-by-step explanation:
here the decay reaction is given as

As we can see here mass number on the product side and reactant side is same so reaction is balanced
and the unstable nuclei is converted into stable nuclei by dissociating into a new stable nuclei and helium nucleus
When stability is attained by emitting helium nuclei then it is known as alpha decay reaction.
so above is an example of alpha decay here