MCAT General Chemistry Discrete Question Set Periodic Table - Properties

Transcription

1 MCAT General Chemistry Discrete Question Set Periodic Table - Properties Question No. 1 of 10 1: What type of bond is H O? Question #01 A. Ionic B. Covalent C. Polar Covalent D. Metallic A: Incorrect. The electronegativity difference isn t great enough to be an ionic bond. B: Incorrect. The electronegativity difference is too great to be a covalent bond. C: Correct. The electronegativity difference is in the polar covalent zone. D: Incorrect. Two non-metals don t form a metallic bond. Electronegativity of H = 2.1 Electronegativity of O = 3.5 Electronegativity difference = 1.4 Answer: (C) Polar Covalent

2 Question No. 2 of 10 Question #02 2: How many sigma and pi bonds are in the following? H H H H C C = C = C O H H Sigma Pi A B. 8 2 C. 8 4 D A: Incorrect. Sigma bonds are the first bonds between each pair of atoms. All other bonds are pi bonds. B: Incorrect. Sigma bonds are the first bonds between each pair of atoms. All other bonds are pi bonds. C: Incorrect. Sigma bonds are the first bonds between each pair of atoms. All other bonds are pi bonds. D: Correct. Sigma bonds are the first bonds between each pair of atoms. All other bonds are pi bonds. Sigma bonds are the first bonds between each pair of atoms. Pi bonds are the 2 nd and 3 rd bond between a pair of atoms There are 10 first bonds There are 2 second bonds Sigma bonds = 10; Pi bonds = 2 Answer: (D) 10, 2

3 Question No. 3 of 10 3: What type of hybridization does the red * atom have? H H H H C C = C* = C O H H Question #03 A. sp B. sp 2 C. sp 3 D. sp 3 d A: Incorrect. This atom has 3 sigma bonds. B: Correct. This atom has 3 sigma bonds. C: Incorrect. This atom has 3 sigma bonds. D: Incorrect. This atom has 3 sigma bonds. An atom with 2 sigma bonds = sp An atom with 3 sigma bonds = sp 2 An atom with 4 sigma bonds = sp 3 The atom has 2 sigma bonds (and 2 pi bonds) This is sp 2 hybridization Answer: (B) sp 2

4 Question No. 4 of 10 4: Which type of compound is the most likely to be soluble in water? Question #04 (A) Ionic (B) Non-polar covalent (C) Polar covalent (D) Metallic A: Correct. Ionic bonds form similar intermolecular forces with water and therefore are the most likely to be soluble. B: Incorrect. Non-polar covalent molecules are not likely to be soluble in water as they only form London Dispersion Forces. C: Incorrect. Although some polar covalent molecules are soluble, there is another choice that is more likely to be soluble. D: Incorrect. Metallic compounds are not likely to be soluble in water. Some polar covalent compounds do dissolve in water, but ionic compounds are more likely to dissolve in water Answer: (A) Ionic

5 Question No. 5 of 10 5: Which compound has the greatest ionic character? Question #05 (A) CsF (B) RbF (C) NaF (D) LiF A: Correct. The greater the difference in electronegativity, the greater the ionic character. B: Incorrect. The greater the difference in electronegativity, the greater the ionic character. C: Incorrect. The greater the difference in electronegativity, the greater the ionic character. D: Incorrect. The greater the difference in electronegativity, the greater the ionic character. The greater the difference in electronegativity, the greater the ionic character. In general, the farther 2 elements are from each other on the periodic table, the greater the difference in electronegativities. Cs & F are the farthest apart as they can get. Answer: (A) CsF

6 Question No. 6 of 10 6: Which scenario would result in the greatest lattice energy? Question #06 (A) Low charge and small radii (B) Low charge and large radii (C) Higher charge and small radii (D) Higher charge and larger radii A: Incorrect. Lattice energy increases with charge and decreases with distance between the center of the two particles. B: Incorrect. Lattice energy increases with charge and decreases with distance between the center of the two particles. C: Correct. Lattice energy increases with charge and decreases with distance between the center of the two particles. D: Incorrect. Lattice energy increases with charge and decreases with distance between the center of the two particles. Lattice energy increases with charge and decreases with distance between the center of the two particles. Therefore, the higher the charge and the smaller the radii, the greater the lattice energy Answer: (C) higher charge and small radii

7 Question No. 7 of 10 7: The following pictures are an example of: Question # O.. N. O O. (A) Isomers (B) Resonance structures (C) Isotopes (D) Lattice structures O = N.. O O O N = O O. A: Incorrect. Isomers have the same chemical formula but different molecular structure. B: Correct. The structures are the same except for the position of the double bond between nitrogen & oxygen. C: Incorrect. Isotopes are two atoms of the same element with a different number of neutrons. D: Incorrect. Lattice structures are found in ionic compounds. The have the same structure but double bonds are in different locations. These are resonance structures Answer: (B) resonance structures

8 Question No. 8 of 10 8: A double bond consists of: Question #08 (A) 1 sigma bond & 1 pi bond (B) 2 sigma bonds (C) 2 pi bonds (D) 1 pi bond A: Correct. The first bond in a multiple bond is a sigma bond and then each additional bond is a pi bond. B: Inorrect. The first bond in a multiple bond is a sigma bond and then each additional bond is a pi bond. C: Incorrect. The first bond in a multiple bond is a sigma bond and then each additional bond is a pi bond. D: Incorrect. The first bond in a multiple bond is a sigma bond and then each additional bond is a pi bond. The first bond in a multiple bond is a sigma bond and then each additional bond is a pi bond. Answer: (A) 1 sigma bond & 1 pi bond

9 Question No. 9 of 10 9: What type of compound is CH 4? Question #09 (A) Ionic (B) Polar covalent (C) Non-polar covalent (D) Metallic A: Incorrect. Ionic bonds are formed between metals and non-metals. B: Incorrect. This electronegativity difference is not great enough to be a polar covalent bond. C: Correct. The electronegativity difference is low enough to be a non-polar covalent bond. D: Incorrect. Non-polar molecules do not form metallic bonds. Carbon & hydrogen atoms always form non-polar covalent bonds. If the bonds are all non-polar covalent and there aren t any lone pairs on the central atom, the compound is non-polar as well. Answer: (C) non-polar covalent

10 Question No. 10 of 10 10: Metallic compounds tend to be: Question #10 (A) Soluble in water (B) Brittle (C) Malleable (D) Liquids A: Incorrect. Metallic compounds are not soluble in water. B: Incorrect. Metallic compounds can be shaped easily they are not brittle. C: Correct. Metallic compounds can be hammered into a sheet (they are malleable). D: Incorrect. Metals tend to be solids. Metallic compounds do not dissolve in water, are malleable and ductile (which is the opposite of brittle), they are malleable and they are rarely liquids Answer: (C) malleable