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Chemistry µIB
2.1b Isotopic Calculations

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Just 5 questions on this quiz - 10 minutes target time

An IB Periodic Table is required.

Calculators are allowed as some of these questions contain more difficult calculations than those on IB multiple choice papers.

atom image
1. Rubidium consists of two isotopes Rubidium-85 and Rubidium-87.
The relative atomic mass of Rubidium is 85.5 (to 1dp).
What is the percentage abundance of the Rubidium-85 isotope?
  • A.   50.0%
  • B.   60.0%
  • C.   75.0%
  • D.   80.0%

2. A sample of an element consisted of 3 isotopes and produced the mass spectrum shown below.

relative atomic mass graph

What is the relative atomic mass of this element?

  • A.   28.1
  • B.   28.3
  • C.   28.9
  • D.   30.4

3. A sample of an unknown element “Z” consists of 3 isotopes as shown below:

Isotope Percentage Abundance /%
64Z 89.43
65Z 7.15
66Z 3.42
 

What is the relative atomic mass of element “Z” to 2dp?

  • A.   64.11
  • B.   64.12
  • C.   64.13
  • D.   64.14
4. The relative atomic mass of Indium is 114.816. Indium consists of two isotopes, 113In and 115In. What is the percentage abundance of the isotope 113In?
  • A.   8.8%
  • B.   9.0%
  • C.   9.2%
  • D.   9.4%

5. What is the relative atomic mass of zirconium from the information shown on the mass spectrum below?

relative atomic mass graph

  • A.   90.9
  • B.   91.3
  • C.   91.7
  • D.   92.1