1. Whib prineiple(o) er rete(o) must be ased to defermise the corrui elecirenle A) Mibau Priaciple i) Ilunt's Rule C) Paell Exclusion Prateiple D) (A) and (B) oaly E) All three 2. Which of the struciures below woald be trigonal planar (a ptasar triangle)? (Tiectrical eharges have beca deliberately omitrof.) (LO 4) A) 1 B) II C) III D) IV D) I and IV 3. What is the formal charge on oxygen in the followiag structure? (LO 1) mathrm(H)_(3) mathrm(CC) equiv mathrm(O) : A) +2 B) +1 C) 0 D) -1 E) -2

1. The correct answer is E) All three.<br /><br />To determine the correct electronic configuration for carbon in its ground state, we need to use all three principles: Aufbau Principle, Pauli Exclusion Principle, and Hund's Rule.<br /><br />The Aufbau Principle states that electrons fill the lowest energy orbitals first before moving to higher energy orbitals. In the case of carbon, it has 6 electrons, so we start by filling the 1s orbital, then the 2s orbital, and finally the 2p orbitals.<br /><br />The Pauli Exclusion Principle states that no two electrons in an atom can have the same set of quantum numbers. This means that each orbital can hold a maximum of two electrons with opposite spins.<br /><br />Hund's Rule states that electrons will fill degenerate orbitals (orbitals with the same energy level) singly before pairing up. In the case of carbon, the 2p orbitals are degenerate, so the electrons will fill them singly before pairing up.<br /><br />By applying all three principles, we can determine the correct electronic configuration for carbon in its ground state: 1s² 2s² 2p².<br /><br />2. The correct answer is D) IV.<br /><br />A trigonal planar structure has a central atom bonded to three other atoms, with all the in the same plane. In the given options, only structure IV has a central atom bonded to three other atoms and all the atoms lying in the same plane.<br /><br />3. The correct answer is D) -1.<br /><br />To calculate the formal charge on oxygen in the given structure ($H_{3}CC\equiv O$), we need to follow the formula:<br /><br />Formal charge = (Valence electrons) - (Non-bonding electrons) - (Bonding electrons) / 2<br /><br />For oxygen, the valence electrons are 6 (since it is in group 16 of the periodic table). In the given structure, oxygen has 4 non-bonding electrons and 4 bonding electrons (2 single bonds with hydrogen atoms and 1 triple bond with carbon).<br /><br />Plugging these values into the formula, we get:<br /><br />Formal charge = 6 - 4 - (4/2) = 6 - 4 - 2 = 0<br /><br />Therefore, the formal charge on oxygen in the given structure is 0.