August 2010 Chemistry Regents #1-10

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

Other Regents Exams

Questions	Answer	Explanations
1 What is the total number of valence electrons in a calcium atom in the ground state? (1) 8     (3) 18 (2) 2     (4) 20	2
2 Which subatomic particles are located in the nucleus of an He-4 atom? (1) electrons and neutrons (2) electrons and protons (3) neutrons and protons (4) neutrons, protons, and electrons	3
3 In the late 1800s, experiments using cathode ray tubes led to the discovery of the (1) electron    (3) positron (2) neutron     (4) proton	1
4 The atomic mass of titanium is 47.88 atomic mass units. This atomic mass represents the (1) total mass of all the protons and neutrons in an atom of Ti (2) total mass of all the protons, neutrons, and electrons in an atom of Ti (3) weighted average mass of the most abundant isotope of Ti (4) weighted average mass of all the naturally occurring isotopes of Ti	4
5 An atom of which element has the largest atomic radius? (1) Fe     (3) Si (2) Mg    (4) Zn	2
6 Which element requires the least amount of energy to remove the most loosely held electron  from a gaseous atom in the ground state? (1) bromine    (3) sodium (2) calcium     (4) silver	3
7 A balanced equation representing a chemical reaction can be written using (1) chemical formulas and mass numbers (2) chemical formulas and coefficients (3) first ionization energies and mass numbers (4) first ionization energies and coefficients	2
8 Every water molecule has two hydrogen atoms bonded to one oxygen atom. This fact supports the concept that elements in a compound are (1) chemically combined in a fixed proportion (2) chemically combined in proportions that vary (3) physically mixed in a fixed proportion (4) physically mixed in proportions that vary	1
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10 Which Group 15 element exists as diatomic molecules at STP? (1) phosphorus    (3) bismuth (2) nitrogen          (4) arsenic	2