Question

When U-238 transmutates into Th-234, what does this represent?

Answer 1

alpha decay:

`""_(92)^(238) "U" -> ""_(90)^(234)"Th" + ""_2^4 "He"`

Explanation:

an alpha particle has a form identical to a helium nucleus.
it contains `2` neutrons and `2` protons.

the mass number of an atom is its number of protons added to its number of neutrons.

the numbers `238` and `234` show the mass number of each isotope.

it can also be found that the mass number of an alpha particle is `2 + 2`, which is `4`.

releasing an alpha particle from an atom would decrease its mass number by `4`.

`238 - 234 = 4`

here, the mass number decreases by `4` in the decay process. this means that the decay was of an alpha particle.