Question

in alpha decay of u - 238:
one alpha particle is emitted
two gamma rays of same energies are emitted and one alpha particle is emitted
two gamma rays of same energies are emitted
two gamma rays of different energies are emitted
radium - 224 undergoes alpha decay as shown:
what is the the appropriate values for a and z and the chemical symbol for x.
$_{88}^{224}ra
ightarrow _{z}^{a}x + _{2}^{4}he$
224 228 220 ra rn th 88 90 86
a
x
z

Explanation:

Step1: Recall alpha - decay concept

In alpha - decay, an alpha particle ($_{2}^{4}He$) is emitted. For U - 238 alpha decay, only one alpha particle is emitted typically and gamma rays are not always associated with the basic alpha - decay process. So for the first question, the answer is based on the definition of alpha - decay.

Step2: Use mass - number and atomic - number conservation for Ra - 224 decay

The mass - number ($A$) and atomic - number ($Z$) are conserved in a nuclear reaction. For the reaction $_{88}^{224}Ra
ightarrow_{Z}^{A}X + _{2}^{4}He$, we know that $A_{Ra}=A_X + A_{He}$ and $Z_{Ra}=Z_X+Z_{He}$. Given $A_{Ra} = 224$, $A_{He}=4$, $Z_{Ra}=88$, $Z_{He} = 2$. Then $A=224 - 4=220$ and $Z=88 - 2 = 86$. The element with $Z = 86$ is Radon ($Rn$).

Answer:

First question: One alpha particle is emitted
Second question:
A. 220
X. Rn
Z. 86