 We are now familiar with electronic configuration and how it helps us determine the position of elements in the periodic table. So, let's solve a couple of interesting questions on electronic configurations. So, let's look at the first question it says, which among the following describes an element with an electronic configuration which is Xe4r145d76s2. So, basically we need to identify this element lies where exactly in the periodic table. Does it belong to the alkaline earth metal, the s-block, the transition metal, d-block, the rare earth metal f-block or the inert gas which is basically in the p-block. As we know, electronic configuration of an atom tells us how the electrons are distributed among the various atomic orbitals. Now from this configuration we can see that the element is positioned after xenon. It has a completely filled electronic configuration that resembles xenon and it has a completely filled 4-if orbitals, 7 electrons in the 5-d orbitals and completely filled 6-is orbitals. So, basically it is a d-orbitals that is incomplete filled. It has only 7 electrons which is less than the maximum it can hold which is 10 electrons, correct? And because the outermost d-orbitals are only partially filled, this means that the element actually is a transition metal or the element belongs to the d-block, alright? Let's now look at the next question. Now the second question says, which of the following electronic configurations represents an atom in an excited state? Okay, so the options are 1 is 2, 2 is 2p1, 1 is 2, 2 is 2p2, 3 is 1, and 1 is 2, 2 is 2, 2p6, okay? Now we know the downstairs of an atom is a state where all of its electrons are in the lowest possible energy levels. That is, the electrons first fill up the lowest energy levels and then proceed to the higher energy levels and this is based on the off-bow principle. So, let us examine our options and see if they follow the off-bow principle or not, okay? Now in the first case, the configuration does follow off-bow principle as all the lower energy levels are filled before moving on to the higher energy level. First the 1s orbitals get filled and then the 2s orbitals and the last electron has entered the higher energy 2p orbital. Now if you look at the second option, you have 1 is 2, 2 is 2, 2p2, and 3 is 1. This configuration does not follow the off-bow principle. Here as we know before filling up the 3s orbitals, all of the 2p orbitals must be completely filled. So that means this is actually an excited state. In an excited state, what basically happens is that an electron has absorbed energy, so it goes from ground state and goes into the excited state. So here it looks like one of the 2p electrons absorbed energy and got excited to the higher energy 3s orbital. But excited state as we know is very temporary. Once the electron emits the absorbed energy, it returns to the ground state. Now the last configuration also follows the off-bow principle, filling each energy level before moving on to the higher energy ones. So this again represents a ground state. So A is a ground state, C is a ground state, and B is our excited state. Okay, so let's look at the last question it says, identify if the given statements are true or false based on the electronic configurations given here. Okay, so the electronic configurations are first one is argon 4s1, second one is xenon 4f1 5d1 6s2 and neon 3s2 3p5 and last one is argon 3d8 4s2. Now argon 4s1 actually refers to our element potassium. So if you look at the periodic table here, okay this is really a small one or maybe you can refer to your textbook periodic table. So you can see that argon 4s1 actually refers to the element potassium. If you look at the first statement it says 1 shows a single oxidation state. Now is this statement true or false? Absolutely true because potassium shows a single oxidation state of plus 1 because it can easily lose this 4s1 electron to achieve the most stable noble gas configuration of argon. And this is why it shows a single oxidation state of plus 1. Alright let's look at the next one it says 2 is a D block element. Now if you examine this electronic configuration you can see that you have partially filled F orbitals in addition to the D orbital. So it is not actually a part of D block but a part of your F block. This element actually belongs to the lanthanide series and to be more specific it is actually the configuration of cerium. That means statement B is actually false. It is an F block element. Let's look at the third statement it says 1 and 3 form a covalent compound. Okay now 1 as we know is potassium and what is element 3? Neon 3s2 3p5 if you look at the periodic table here again it actually refers to the element chlorine and chlorine is a nonmetal. So a bond formed between a metal and a nonmetal is ionic in nature and not covalent. So they combine with each other by loss of electron. Potassium loses 1 electron and chlorine accepts 1 electron to form the ionic compound and they don't share electrons in order to form a covalent compound. So that means statement C is also false. Let's look at the last statement it says that element 4 forms colored complexes. Now that is actually true. This element refers to nickel which is a transition element and belongs to D block and as we know transition elements form vibrantly colored complexes. In fact nickel forms complexes which are mostly green or blue in color. So based on this you can see that statements A and D are true while B and C are false.