Question

1. which element has the noble gas configuration of ar4s²3d⁶? nickel manganese argon iron clear all

Explanation:

Step1: Recall noble - gas core notation

The noble - gas core notation [Ar] represents the electron configuration of argon (Ar) which has 18 electrons. The additional part of the electron configuration is $4s^{2}3d^{6}$.

Step2: Calculate the total number of electrons

Argon has 18 electrons. Adding the 2 electrons in the 4s orbital and 6 electrons in the 3d orbital, we get $18 + 2+6=26$ electrons.

Step3: Identify the element

The atomic number of an element is equal to the number of electrons in a neutral atom. The element with an atomic number of 26 is iron (Fe).

Answer:

Iron