June 2014 Chemistry Regents #31-35

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Questions

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Explanations

31 Which notations represent different isotopes of the element sodium?

(1) 32S and 34S (3) Na+ and Nao

(2) S2- and S6+ (4) 22Na and 23Na

4 link Isotopes have same # of protons and different # of neutrons, so the mass number is different
32  Which electron configuration represents the electrons in an atom of Ga in an excited state?

(I) 2-8-17-3    (3) 2-8-18-3

(2) 2-8-17-4     (4) 2-8-18-4

2 link the ground state configuration is 2-8-18-3

promote an electron to make it excited

2-8-17-4

33 Which statement describes the general trends in electronegativity and first ionization energy as the elements in Period 3 are considered in order from Na to Cl?

(1) Electronegativity increases, and first ionization energy decreases.

(2) Electronegativity decreases, and first ionization energy decreases.

(3) Electronegativity and first ionization energy both increase.

(4) Electronegativity and first ionization energy both decrease.

3 link

link2

look up the values on table S

 

34 What is the gram-formula mass of Fe(NO3)3?

(1) 146 g/mol (3) 214 g/mol

(2) 194 g/mol (4) 242 g/mol

4 link Fe=56

N=3 x 14=52

O=9 x 16=144

56+52+144=242g/mol

35  Given the balanced equation representing a reaction:

Al2(SO4)3 +6NaOH ==> 2Al(OH)3 + 3Na2SO4

The mole ratio of NaOH to Al(OH)3 is

(1) 1:1  (2) 1:3

(3) 3:1  (4)  3:7

3 link THE MOLE RATIO IS THE COEFFICIENT RATIO

6NaOH: 2Al(OH)3

reduces to 3:1

 

Questions 1-5 Questions 6-10 Questions 11-15 Questions 16-20 Questions 21-25 Questions 26-30 Questions 31-35 Questions 36-40 Questions 41-45 Questions 46-50

Question 51-54 Questions 55-56 Questions 57-58 Questions 59-61 Questions 62-65 Questions 66-69 Questions 70-72 Questions 73-75  Questions 76-79  Questions 80-82  Questions 83-85

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