Question

Atomic number of an ${\text{X}}$ is $34$, it belongs to
A.${\text{IV period,VIA group}}$
B.${\text{IV period,IIA group}}$
C.${\text{V period,IIIB group}}$
D.${\text{IV period,VIIA group}}$

Answer 1

Hint: The electronic configuration of ${\text{X}} = 1{s^2},2{s^2},2{p^6},3{s^2},3{p^6},3{d^{10}},4{s^2},4{p^4}$.The number of protons which is always equal to the number of electrons in the neutral atom, is known as the atomic number. The group number depends on the number of valence electrons and the period number is valence shell number.

Complete step by step answer:
Neutral atoms of an element contain an equal number of protons and electrons.
The electronic configuration of${\text{X}} = 1{s^2},2{s^2},2{p^6},3{s^2},3{p^6},3{d^{10}},4{s^2},4{p^4}$. It has $2$ electron in ${\text{K}}$ shell, $8$ electron in ${\text{L}}$ shell, $18$ electron in ${\text{M}}$ Shell,$6$ electron in the outermost shell ${\text{N}}$.
It is nonmetal and it belongs to $p$ block. Due to its various properties sometimes it is considered as metalloid as well. Its $7$ isotopes are available in nature. Out of seven naturally occurring isotopes, five isotopes are stable and two are unstable. An electron of an atom, located in the outermost shell of the atom that can be transferred to or shared with another atom is known as valence electron.
Now in the electronic configuration of ${\text{X}}$ we can see that the valence electron entering into the ${4^{th}}$ shell i.e.${\text{(n = 4)}}$ the elements belongs to the ${\text{IV}}$ period and it has 6 electrons in the valence shell, so its outer configuration belongs to of ${\text{VIA}}$ group.

So the correct answer is Option A.

Note:
The period of an element corresponds to the principal quantum number of the valence shell. The block of an element corresponds to the type of orbital which receives the last electron. The group of an element is predicted by the number of electrons in the valence shell or penultimate shell which is given below; For ${\text{s}}$-block elements, group number = no. of valence electrons.
For ${\text{p}}$-block elements, group number = $10$ + number of electrons in the valence shell.
For ${\text{d}}$-block elements, group number = number of electrons in a ${\text{(n - 1)d}}$ subshell + number of electrons in valence shell.