Question

which equation summarizes the alpha decay of $^{210}_{85}at$?
a. $^{210}_{85}at
ightarrow^{206}_{83}bi + ^{4}_{2}he$
b. $^{210}_{85}at
ightarrow^{206}_{83}bi+_{ - 1}^{0}e$
c. $^{210}_{85}at
ightarrow^{210}_{86}rn + ^{4}_{2}he$
d. $^{210}_{85}at
ightarrow^{210}_{86}rn+_{ - 1}^{0}e$

Explanation:

Step1: Recall alpha - decay concept

In alpha - decay, an atomic nucleus emits an alpha particle ($^4_2$He). The mass number of the parent nucleus decreases by 4 and the atomic number decreases by 2.

Step2: Analyze the parent nucleus

The parent nucleus is $^{210}_{85}$At. After alpha - decay, the mass number of the daughter nucleus will be $210 - 4=206$ and the atomic number will be $85 - 2 = 83$. The element with atomic number 83 is Bi (bismuth). The emitted particle is an alpha particle $^4_2$He.

Answer:

A. $^{210}_{85}\text{At}\to^{206}_{83}\text{Bi}+^{4}_{2}\text{He}$