Start by finding the noble gas core. For tungsten, this will be xenon as this is the noble gas that is closest to it.

The normal electron configuration for  is as follows:

Recall that electrons are lost in the highest energy level subshell first.

 has lost  electrons. It will lose the first two electrons from the  shell, then it will lose  electron from the  shell, giving it the following electron configuration:

Start by finding the noble gas core. For iron, this will be argon as this is the noble gas that is closest to it.

Next, recall that since the  orbitals are higher in energy that the  orbitals, electrons will be lost from the  orbital first.

The normal electron configuration for  is as follows:

 has lost  electrons. It will lose the first two electrons from the  shell, then it will lose  electron from the  shell, giving it the following electron configuration:

Electrons of an atom are located within electronic orbitals around a nucleus. The electrons of each atoms have their own specific energy level called principal energy level. When electrons are excited by absorbing energy the electrons can jump to a high energy level. Then when an electron drops back to a lower energy level the electron emits the energy. Therefore, when an atom moves from a lower energy state to a higher energy state. the electrons absorb energy. 

Each element has a unique electron configuration that represents the arrangement of electrons in orbital shells and sub shells. There are four different orbitals, s, p, d, and f that each contain two electrons. The p, d, and f orbitals contain subshells that allow them to hold more electrons. The orbitals for an element can be determined using the periodic table. The s-block consists of group 1 and 2 (the alkali metals) and helium. The p-block consists of groups 3-18. The d-block consists of groups 3-12 (transition metals), and the f-block contains the lanthanides and actinides series. Using this information we can determine the full electron configuration of sodium.  

To do this, start at hydrogen  located at the top left of the periodic table. Hydrogen  and helium  are in the first s orbital and account for . Next, we move to the second s-orbital that contains lithium (Li) and beryllium (Be), which accounts for . Then we move to boron, carbon, nitrogen, oxygen, fluorine, and neon, which are all in the p-block and account for . There is no 1p orbital. Finally, we are at sodium, which is in the s-block and accounts for . Therefore the full electron configuration of sodium is . 

Each element has a unique electron configuration that represents the arrangement of electrons in orbital shells and subshells. There are four different orbitals, s, p, d, and f that each contain two electrons. The p, d, and f orbitals contain subshells that allow them to hold more electrons. The orbitals for an element can be determined using the periodic table. The s-block consists of group 1 and 2 (the alkali metals) and helium. The p-block consists of groups 3-18. The d-block consists of groups 3-12 (transition metals), and the f-block contains the lanthanides and actinides series. Using this information we can determine the electron configuration of iodine in nobel gas configuration.  

The nobel gas configuration is a short hand to writing out the full electron configuration. To do this, start at the nobel gas that come before the element of interest. In the case of iodine, the nobel gas is krypton. Therefore, the electron configuration will begin with , and this will be the new starting place for the electron configuration.

After krypton comes the s-block, which contains elements with the atomic numbers 37 and 38 that account for . Then comes the d-block containing elements 39-48 that account for . Finally comes the p-block containing elements 49-53 that account for . Therefore, the electron configuration of iodine in nobel gas configuration is . 

The absorption of energy excites electrons to higher energy levels, from a lower  to a higher one. Since electron shells grow increasingly closer in energy and  increases, the highest gaps occur between lower level shells. Thus, in this question, the largest gap between any two principle quantum number occurs between the first energy level and the third energy level.

2d is a non-existent energy shell because its principle quantum number, , does not exceed its orbital angular momentum quantum number, . This is easily observable on the periodic table, where it is shown that the d-sub shell is only available for energy levels greater than or equal to three. All other answer choices obey the rule that the orbital angular momentum quantum number is less than the principle quantum number. 

The correct answer is that 4n is larger in size than 2n.  

When it comes to quantum numbers, n refers only to size or the atom, or electrons' distance from the nucleus; n is the principal quantum number.  

l is expressed as  and is therefore dependent on the n value; l describes the shape of the orbital (spherical, dumbbell, etc.).  

m_l values range from  to  and describe the orientation of the orbital.  

m_s values are either  or  and represent electron spin.  

Electrons of an atom are located within electronic orbitals around a nucleus. The electrons of each atoms have their own specific energy level called principal energy level. When electrons are excited by absorbing energy the electrons can jump to a higher energy level. When an electron drops back to a lower energy level, the atom emits energy. Therefore, when neon atoms in a neon sign emit light, the electrons are moving from a higher principal energy level to a lower principal energy level. 

To solve this problem we need to use the following equation:

where, 

 = speed of light = . The speed of light is constant. 

 = wavelength (units = )

 = frequency (units =  or )

Now we can plug the wavelength and the speed of light into the equation above and solve for frequency.