| Date | May 2012 | Marks available | 1 | Reference code | 12M.2.sl.TZ2.4 |
| Level | SL | Paper | 2 | Time zone | TZ2 |
| Command term | Determine | Question number | 4 | Adapted from | N/A |
Question
\(^{{\text{131}}}{\text{I}}\) is a radioactive isotope of iodine.
Define the term isotope.
[1]
a.i.
Determine the number of neutrons in one atom of iodine-131.
[1]
a.ii.
Markscheme
atoms which have same atomic number but different mass number / atoms of the same element which have different numbers of neutrons / atoms with the same number of protons but different numbers of neutrons / atom of an element with a fixed number of protons but a number of neutrons which can be variable;
a.i.
78;
a.ii.
Examiners report
In (a)(i), the word atoms was frequently omitted from the definition; it is accepted that it would have been preferable to ask for the definition of isotopes of an element as specified in the syllabus.
a.i.
The answer in (ii) was generally correct.
a.ii.
