Answer:
B and D
Step-by-step explanation:
Option A is incorrect as it is a neutralization reaction. Option C is incorrect as it an oxidation reaction, the rusting of iron to form iron oxide.
Option B and D are nuclear reactions called alpha decay.
In an alpha decay, a helium atom is released, and the daughter nucleus formed has atomic number 2 less than the parent nucleus and mass number 4 less than the parent nucleus.