January 2013 Chemistry Regents #73-76

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  Base your answers to questions 73 through 76 on the information below.

The element boron, a trace element in Earth’s crust, is found in foods produced from plants. Boron has only two naturally occurring stable isotopes, boron-10 and boron-11.

73 Compare the abundance of the two naturally occurring isotopes of boron. [1]

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Boron-11 is about four times more abundant than boron-10.

The B-10 is less abundant.

74 Write an isotopic notation of the heavier isotope of the element boron. Your response must include the atomic number, the mass number, and the symbol of this isotope. [1]

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115B

75 State, in terms of subatomic particles, one difference between the nucleus of a carbon-11 atom and the nucleus of a boron-11 atom. [1]

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0The carbon-11 nucleus has one more proton than the nucleus of boron-11.

A B-11 atom has a different number of neutrons than a C-11 atom.

76 One sample of a green vegetable contains 0.0035 gram of boron. Determine the total number of moles of boron in this sample. [1]

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0.000 32 mol

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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

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