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June 2005 Chemistry Regents #31-40
Highlight to reveal answers and explanations
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Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50 |
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Questions |
Answer | Explanations |
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4 | 0+1e is a positron Table O |
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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 |
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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 |
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3 | Br-Br same element Zero electronegativity difference |
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Questions 1-10 Questions 11-20 Questions 21-30 Questions 31-40 Questions 41-50 |
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