As a result of a chain of radioactive transformations, the ichotope thorium 90 232 Th turned

As a result of a chain of radioactive transformations, the ichotope thorium 90 232 Th turned into an isotope of lead 82 208 Pb Determine a) the number of alpha decays in this chain b) the number of beta decays

According to radioactive series, the conversion of the thorium isotope 90 232 Th

in the lead isotope 82 208 Pb occurs in the following order:

the thorium isotope 90 232 Th is converted into the radium isotope 88 228 Ra (alpha decay);

the radium isotope 88 228 Ra is converted to the actinium isotope 89 228 Ac (beta decay);

actinium isotope 89 228 Ac is converted to thorium isotope 90 228 Th (beta decay);

thorium isotope 90 228 Th is converted to radium isotope 88 224 Ra (alpha decay);

isotope of radium 88 224 Ra is converted into isotope of radon 86 220 Rn (alpha decay);

isotope of radon 86 220 Rn is converted to isotope of polonium 84 216 Po (alpha decay);

the polonium isotope 84 216 Po is converted to the lead isotope 82 212 Pb (alpha decay);

lead isotope 82 212 Pb is converted to bismuth isotope 83 212 Bi (beta decay).

The bismuth isotope 83 212 Bi is characterized by alpha or beta decay, consider them:

1) the bismuth isotope 83 212 Bi is converted into the thallium isotope 81 208 Tl (alpha decay);

thallium isotope 81 208 Tl is converted into a stable lead isotope 82 208 Pb (beta decay).

2) the bismuth isotope 83 212 Bi is converted into the polonium isotope 84 212 Po (beta decay);

the isotope of polonium 84 212 Po is converted into the stable isotope of lead 82 208 Pb (alpha decay).

Thus, the transformation of the 90 232 Th isotope into the lead isotope 82 208 Pb occurs:

a) 7 alpha decays

b) 5 beta decays