June 2005 Chemistry Regents #31-40

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

 

Questions

Answer Explanations
4 0+1e is a positron  Table O
3 memorize that
33 An electron in an atom moves from the ground state to an excited state when the energy of the electron
(1) decreases
(2) increases
(3) remains the same
2 increases
34 Which symbol represents a particle that has the same total number of electrons as S2?
(1) O2    (3) Se2
(2) Si       (4) Ar
4 S2  has 16 + 2 more electrons =18 total

same as Ar

3 between 141 and 171
36 Which substance has a chemical formula with the same ratio of metal ions to nonmetal ions as in potassium sulfide?
(1) sodium oxide
(2) sodium chloride
(3) magnesium oxide
(4) magnesium chloride
1 same ratio would be elements from the same groups as the ones being replaced
37 The molecular formula of glucose is C6H12O6. What is the empirical formula of glucose?
(1) CHO     (3) C6H12O6
(2) CH2O    (4) C12H24O12
2 reduced = empirical
38 According to Reference Table F, which of these
compounds is the least soluble in water?
(1) K2CO3        (3) Ca3(PO4)2
(2) KC2H3O2     (4) Ca(NO3)2
3 Phosphates are insoluble
39 A sample of a substance containing only magnesium and chlorine was tested in the laboratory and was found to be composed of 74.5% chlorine by mass. If the total mass of the sample was 190.2 grams, what was the mass of
the magnesium?
(1) 24.3 g (3) 70.9 g
(2) 48.5 g (4) 142 g
2 25.5% Mg x190.2g=48.5g Mg
3 Br-Br same element Zero electronegativity difference

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