Question

When ${}_{88}^{226}Ra$ emits an $\alpha -$ particle, the new element formed belonged to:
A. Third group
B. Zero group
C. Fourth group
D. Second group

Answer 1

We have to remember that the Radium (symbol $Ra$) is an alkaline earth metal and its atomic number is $88$. It has $33$ known isotope and all isotopes are highly radioactive and radium $- 226$ is highly stable among them.
Conversion of one or two chemical elements or an isotope (or induced by bombarding it with an energetic particle) into another element (also known as nuclide) is called the nuclear reaction. This is also called nuclear transmutation.

Complete step by step answer:
We must remember that radioactive decay is a process, in which the unstable nucleus loses energy in the form of emitting radiation to form stable nuclides. The emitting radiation may be alpha particles, beta emission, positron emission, gamma rays and an electron capture. The original element and the newly formed nucleus after radiation is called parent and daughter nucleus respectively.
Alpha ($\alpha$or${}_2^4He$) particle emission: The atomic nucleus decays and emits alpha particles, with an atomic number is reduced by two and mass number is reduced by four.
General reaction is,
${}_Z^AY \to {}_{Z - 2}^{A - 4}X + {}_{{}_2}^4He$
${}_{88}^{226}Ra$ emits alpha particle and the nuclear reaction is,
${}_{88}^{226}Ra \to {}_{86}^{222}X + {}_{{}_2}^4He$
In the above nuclear reaction, the daughter nucleus formed atomic number is$86$. In the periodic table, atomic number $86$ is Radon, symbol is$Rn$, radon have zero valence (because their atoms cannot combine with other elements) in the periodic table and once they had labeled group zero.

So, the correct answer is Option B.

Note: We must remember that in nuclear reactions, protons and neutrons are not destroyed they are sifts around them. Radium is used as a radiation source in industrial radiography. And sometimes used in medical treatment for prostate cancer, which has spread to the bones. If the element contains the same atomic number (same number of protons) but different mass number (different number of neutrons) then that is called isotopes. For example: Hydrogen contains three isotopes, they are protium $\left( {{}_1^1H} \right)$, deuterium $\left( {{}_1^2H} \right)$, and tritium $\left( {{}_1^3H} \right)$.