Can you show me the answer and explain?

C

Explanation:

looking at a periodic table X is fluorine and Y is potassium

Fluorine is in group 7 and forms a 1- charge (which gains electrons) and potassium is in group 1 and forms a 1+ charge (which loses electrons)

Fluorine (X) has an electronic structure of 2,7 and needs to gain an electron from Potassium (Y) to have a full outer shell and potassium has an electronic structure of 2,8,8,1 so needs to lose an electron to have a full outer shell as well. This means that the electron that potassium (Y) has lost is given away to fluorine (X), so both elements become stable.

This is known as ionic bonding where metals (like potassium) lose electrons and non-metals (like fluorine) gain electrons to become more stable, forming ions

Any further clarification let me know

it is to be noted that an alpha particle is an helium nucleus. so it contains 2 protons 2 neutrons and has a mass number of 4. when alpha decay particles are ejected from the nucleus it gets transformed into an atom which has atomic number less than 2 and a mass number less than 4.

an equation that could represent alpha decay is radium 226 decay of alpha particle forms radon 222.

→

the atomic number will stay the same no matter how many electrons it has, so it doesn’t decrease nor increase. it’ll only change with a different number of protons