Question

When Plutonium-239 undergoes alpha decay, it becomes A) curium-241 + an alpha particle B) uranium-235 + an alpha particle C) neptunium-237 + and alpha particle D) plutonium-237 + and alpha particle

Answer 1

An alpha particle is composed of two protons and two electrons.

As a result, in alpha decay, the nucleus that decays loses two protons and two neutrons. So the mass number (239 in this case) decreases by 4.

239 - 4 = 235,

So the new nucleus must be B) Uranium-235, as it is the only one of the options that has an atomic mass of 235.

Answer 2

The correct answer is option B.

Step-by-step explanation:

Alpha decay: In this process, alpha particles is emitted when a heavier nuclei decays into lighter nuclei. The alpha particle released has a charge of +2 units.

The general alpha decay reaction is given as:

`_Z^A\textrm{X}\rightarrow _(Z-2)^(A-4)\textrm{Y}+_2^4\alpha`

So, when Pu-239 undergoes alpha decay it gives Uranium-235 and alpha particle.

`_(94)^(239)\textrm{Pu}\rightarrow _(92)^(235)\textrm{U}+_2^4\alpha`

Hence,the correct answer is option B.