2024 LATEST CHEM 120 WEEK //CHEM 120 FINAL EXAM |TEST BANK| QUESTIONS AND ANSWERS GRADED A+ ACTUAL EXAM B - CORRECT ANSW -How many bonds can nitrogen have? Which rule or principle should be used? A) Five bonds; octet rule. B) Three bonds; octet rule. C) Three bonds; the Hund's rule. D) Five bonds; the Aufbau Principle. C - CORRECT ANSW -When two hydrogen atoms meet, they will attract to each other and form a bond (and a H2 molecule). Why? A) Because electrons like to stay together. B) Because electrons like to be paired up. C) Because there is attraction between the electron in one hydrogen atom and the nucleu s of another hydrogen atom. D) Gravitational attraction between two atoms binds two hydrogen atoms (or any two atoms) together into a molecule. A - CORRECT ANSW -How do you determine the number of electron domains on the central atom? A) Draw Lewis struc ture of the compound, then add up the numbers of lone electron pair, single bond, double bond, and triple bond. B) The # of electron domains = the # of valence electrons C) The # of electron domains = the number of atoms the central atom is bonded to. D) The # of electron domains = the # of valence electrons divided by 2 B - CORRECT ANSW -Indicate partial charges on each atom of the following two bonds: C -Br and O -N. A) Carbon has partial negative charge and bromine has partial positive charge; both oxygen and nitrogen have no charge. B) Carbon has partial positive charge and bromine has partial negative charge; oxygen has partial negative charge and nitrogen has parti al positive charge. C) Carbon has partial negative charge and bromine has partial positive charge; oxygen has partial positive charge and nitrogen has partial negative charge. D) Carbon has partial positive charge and bromine has partial negative charge; o xygen has partial positive charge and nitrogen has partial negative charge. A - CORRECT ANSW -In which of the above structures, the nitrogen atom carries a negative formal charge? A) a B) b C) c D) d B - CORRECT ANSW -In which of the above Lewis structure s, the oxygen atom carries a positive formal charge? A) a B) b,c C) a,d D) c E) d D - CORRECT AN SW-Which of the following compounds exists? A) CH3CH3CH3 B) (CH3) 2CCH3 C) CH3CHCH2CH3 D) (CH3)2CHCH3 C - CORRECT ANSW -Indicate hybridization of oxygen atom in the following compounds: H2O, H2C=O, H3O+, HO -, and CO A) sp3, sp3, sp3, sp3, sp B) sp3, sp2, sp2, sp, sp C) sp3, sp2, sp3, sp3, sp D) sp, sp2, sp2, sp, sp A - CORRECT ANSW -Indicate hybridization of carbon in the above compounds. A) sp3, sp2, sp3, sp2 B) sp3, sp2, sp2, sp2 C) sp3, sp3, sp3, sp2 D) sp3, sp3, sp3, sp3 D - CORRECT ANSW -What is the bond angle in a perfect tetrahedron molecule like CH4? A) 120 B) 0 C) 180 D) 109.5 A - CORRECT ANSW -When SO3 reacts water, sulfuric acid (H2SO4) is formed. Is SO3 a BrØnsted -Lowry acid? A) No, it is not a BrØnsted -Lowry acid. B) Yes, it is a BrØnsted -Lowry acid. B - CORRECT ANSW -Conjugate acid and base is a concept unique to BrØnsted -Lowry acids and bases. Which of the pairs below a re not conjugate acid and base? a. H2SO4 and SO42 - b. H2CO3, CO2 c. HCl and Cl2 d. H3O+ and HO - e. HBr and Br - A) a,b,c B) a,b,c,d C) a,b D) a,b,c,d,e E) e C - CORRECT ANSW -What is the pH value of an acidic solution with a proton molar concentration of 1 0^-3? A) 0.001 B) 0.003 C) 3 D) -3 A - CORRECT ANSW -Gastric acid is composed of hydrochloric acid (HCl) - a strong acid. The pH range of gastric acid is 1.5 to 3.5 in the human stomach. If the HCl concentration is 0.5 mole/liter in John's stomach, is the pH value of his gastric acid in the normal range, too high, or too low? A) Too low B) Too high C) In the normal range. D - CORRECT ANSW -Which of the compounds below is the smallest carboxylic acid? (Some carboxylic acids can found in Section 2.3) 58% A) Methyl alcohol (MeOH) B) Methylam ine (CH3NH2) C) Acetic acid D) Formic acid A - CORRECT ANSW -Hydronium (H3O+) has a pKa of -1.7, and is the strongest acid that can exist in water. A carboxylic acid (RCOOH) can be protonated by hydronium. So, the pKa of RCOOH:
