Correct answer = C. Correct answer = D. Correct answer = C. Correct answer = A

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Vernon Walters
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1 Copper has atomic # 29, so it must have 29 protons. 2+ means that it has lost 2 electrons, so there are 27. Correct answer = D Tetra = 4, so A is not correct Cannot use Greek prefixes when there is a metal in the compound, so B is not correct Chromium s oxidation # is +3 because it is cancelled out by the three negative charges of chlorine. Oxygen is not a metal, so D is out. Ionic bonds are between metals & nonmetals, so A is out. Hydrogen bonds are not actually bonds, plus why would oxygen form a hydrogen bond? When you draw the Lewis structure for O 2, it ends up with a double bond. Correct answer = A Don t really know about the velocity of alpha particles, but the others are true statements. You must go back and reread the question to make sure you are answering the question they ask. The alpha particles went straight through because there was nothing in their way.

2 Correct answer = D Like #1, 2- charge indicates a change in the number of electrons in this case the sulfur would have 2 more electrons that a neutral atom of sulfur Correct answer = A 74 mmhg = pressure 75 o C = temp (change to K) L = volume? = moles Use PV=nRT Be sure to convert to the correct units as appropriate. Correct answer = D The only thing we can learn about a mass vs. volume graph is the density. Estimating a little bit, at 100 g (on y-axis), the temp is about 9 cm 3 (on x- axis). You can do this with other points on the graph, but your answer is going to come out to be just a little over 11 g/cm 3. If you look at the chart at the bottom of page 1 of the Reference Tables, lead is the metal with a density of just over 11 g/cm 3.

3 Answer choice C ends with 3p and answer choice D ends with 3d, so neither of these are in the s-block. The correct answer is B because the HOEL corresponds to the period where the element is located. You could also count up the arrows and determine the element and pick the one that corresponds to Na or Mg. 1 mole of gas at STP = 22.4 L 2.00 moles x 22.4 L = 44.8 L 1 mole Correct answer = A In a stoichiometry problem where you are given a number of liters and you are asked for a number of liters, only the mole ratio step is required. (If you do all three steps, it will come out to the correct answer, it is just slightly shorter to use the short cut.) 40.0 L CO 2 = x moles C 2H x = 80 x = 20 L

4 Correct answer = A 2.62 g Fe x 1 mole Fe = moles Fe = g g S x 1 mole S = moles S = g :1 mole ratio means that the subscripts of each element are 1. A is not correct because they are different elements, so they have different # of protons. B is not correct because covalent bonds occur between 2 or more nonmetals K and Ca are metals. D is not correct because that would only be true for Cl- because it gained electrons. Correct answer = A Region I is increasing temperature in the solid phase. Region II is changing from solid liquid. Region III is increasing temp in the liquid phase. Region IV is changing from liquid gas. Region V is increasing temp in the gas phase.

5 Correct answer = D In a nuclear equation, the top numbers need to add up to the same thing on both sides of the arrow, and same with the bottom K 42 20Ca + 0-1e A catalyst will change where the peak of the graph is, so anything that is measured to the peak will change. The only one of these answer choices that doesn t go to the peak is IV.

6 Correct answer = A One product = synthesis (See p. 6 of Ref Tables) Look for answer that has the same number of each element on each side of the arrow. namava = nbmbvb 1 H at beginning of HNO 3, 1 OH at the end of KOH = 1. x Bronsted Lowry acid can lose an H +1 Bronsted Lowry base can gain an H +1 Water (HOH, H 2O) is the most common example of an amphoteric substance a substance that can act as either an acid or a base

7 Correct answer = D Ba s oxid # = +2 (group 2) O s oxid # = -2 (group 16) S s oxid # = x (1. +2) + (1. x) + (4. -2) = 0 Solve for x and it equals +6 Correct answer = D

9 Correct answer = A Correct answer = A

10 Correct answer = D Correct answer = A

11 Correct answer = A

12 Correct answer = D

13 Correct answer = D The material covered in question #39 is no longer a tested objective on the NCFE. Correct answer = A

14 Correct answer = D

15 Correct answer = A Correct answer = D

16 Correct answer = D

17 Correct answer = A

18 Correct answer = A

19 Correct answer = D Correct answer = A Correct answer = D

NCFE Released Items. Correct Answer = D Number of protons = atomic number

NCFE Released Items. Correct Answer = D Number of protons = atomic number Correct Answer = D Number of protons = atomic number Pa = 91 protons U = 92 protons Np = 93 protons Pu = 94 protons Info from Unit 3 Correct Answer = B Valence electrons are the electrons in the HOEL.