January 2013 Chemistry Regents #31-40

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Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50

Questions 51 Questions 52-54 Questions 55-58 Questions 59-61 Questions 62-65 Questions 66-69

Questions 70-72 Questions 73-76 Questions 77-79 Questions 80-82 Questions 83-85

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31 Which electron configuration represents a selenium atom in an excited state?

(1) 2-7-18-6

(2) 2-7-18-7

(3) 2-8-18-6

(4) 2-8-18-7

2 Link must have 34 electrons

moving one to a higher energy level

NOT the configuration in the Reference Tables

32 When the hydronium ion concentration of a solution is increased by a factor of 10, the pH value of the solution

(1) decreases 1 pH unit

(2) decreases 10 pH units

(3) increases 1 pH unit

(4) increases 10 pH units

1 Link increase by 10 pH changes by 1

hydronium is H3O+ so it becomes more acidic, pH decrease

33 In the formula XF2, the element represented by X can be classified as a

(1) Group 1 metal

(2) Group 2 metal

(3) Group 1 nonmetal

(4) Group 2 nonmetal

2 Link X has a charge of 2+, because each F is 1-group 2

 

34 Which compound has the smallest percent composition by mass of chlorine?

(1) HCl    (3) LiCl

(2) KCl   (4) NaCl

2 Link the most massive will have the smallest percent of Cl

35 Given the incomplete equation representing a reaction:

2C2H14 + ____ O2 --> 12 CO2 + 14 H2O

What is the coefficient of O2 when the equation is completely balanced using the smallest whole-number coefficients?

(1) 13

(2) 14

(3) 19

(4) 26

3 Link add up the oxygen's on the right and divide by 2 to get the coefficient on the left

36 What is the oxidation number of iodine in KIO4?

(1) +1 (3) +7

(2) -1 (4) - 7

3 Link since each O is -2 and K is +1 I must be +7

 

37 What is the chemical formula for zinc carbonate?

(1) ZnCO3

(2) Zn(CO3)2

(3) Zn2CO3

(4) Zn3CO3

1 Link use table E and the charges...see link

38 Which statement explains why a molecule of CH4 is nonpolar?

(1) The bonds between the atoms in a CH4 molecule are polar.

(2) The bonds between the atoms in a CH4 molecule are ionic.

(3) The geometric shape of a CH4 molecule distributes the charges symmetrically.

(4) The geometric shape of a CH4 molecule distributes the charges asymmetrically.

3 Link

lower the volume first

SNAP= symmetrical nonpolar asymmetrical polar

 

39 Which atom in the ground state has the same electron configuration as a calcium ion, Ca2+, in the ground state?

(1) Ar

(2) K

(3) Mg

(4) Ne

1 Link Ca2+ has 18 electrons

Atoms of Ar have 18 protons and 18 electrons

atoms are neutral

40 In the compound KHSO4, there is an ionic bond between the

(1) KH+ and SO42- ions

(2) KHSO3+ and O2- ions

(3) K+ and HS- ions

(4) K+ and HSO4- ions

4 Link HSO4- is a polyatomic ion

Table E

Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50

Questions 51 Questions 52-54 Questions 55-58 Questions 59-61 Questions 62-65 Questions 66-69

Questions 70-72 Questions 73-76 Questions 77-79 Questions 80-82 Questions 83-85

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