Answer:
Iron and Oxygen
Explanation:
Fe is Iron and O2 is Oxygen
<u>Answer:</u> The electronic configuration of gallium is written below and number of valence electrons is 3.
<u>Explanation:</u>
Electronic configuration is defined as the representation of electrons around the nucleus of an atom.
Number of electrons in an atom is determined by the atomic number of that atom.
Valence electrons are defined as the electrons present in the outermost shell of an atom.
We are given:
An element Gallium having atomic number as 31.
Number of electrons = 31
Electronic configuration of Gallium is: 
This element has 3 electrons in its outermost shell. So, the number of valence electrons is 3
Hence, the electronic configuration of gallium is written below and number of valence electrons is 3.
Answer: This comes to bear because of what is known as resonance effect Or mesomeric effect In chemistry.
Explanation:
The concept of resonance effect reveals about the polarity induced in a molecule by the reaction between a lone pair of electron and a pi bond. It also occurs by the interaction of 2 pi bonds in the adjacent atoms.