Question

Which element has 3 valence electrons in the 4d sublevel? A. V B. Nb C. Cu D. Tl

Answer 1

Nb, the transition metal(d) subshell will always be n-1, meaning the 3d subshell will be in row(period) 4. So if it’s 4d then it is row(period) 5, and if it has 3 valence electrons then the element is located in column V, or the third column in the transition metal section.

Answer 2

Answer: The correct answer is Option B.

Explanation:

Valence electrons are defined as the electrons which are present in outermost shell of an atom. This is determined by the electronic configuration of an element.

For the given options:

Option A: Vanadium (V)

The atomic number of this atom is 23 and number of electrons that are present are 23. The electronic configuration of vanadium is:

$V:[Ar]3d^34s^2$

This element does not have 3 electrons in 4d-subshell.

Option B: Niobium (Nb)

The atomic number of this atom is 41 and number of electrons that are present are 41. The electronic configuration of niobium is:

$Nb:[Kr]4d^35s^2$

This element have 3 electrons in 4d-subshell.

Option C: Copper (Cu)

The atomic number of this atom is 29 and number of electrons that are present are 29. The electronic configuration of copper is:

$Cu:[Ar]3d^{10}4s^1$

This element does not have 3 electrons in 4d-subshell.

Option D: Thallium (Tl)

The atomic number of this atom is 81 and number of electrons that are present are 81. The electronic configuration of thallium is:

$Tl:[Xe]4f^{14}5d^{10}6s^26p^1$

This element does not have 3 electrons in 4d-subshell.

Hence, the correct answer is Option B.