Question detail
Which of the following ions has a charge of -2?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
Chemical bonds, ionic, covalent and metallic
Question
- A. O^2-
- B. Na+
- C. Mg^2+
- D. Cl-
Answer
The correct option is O^2-. This answer is correct because it matches the approved learning objective to use group number to work out the charge on ions from Group 1, Group 2, Group 6 and Group 7 elements in the subtopic Ionic bonding.
Explanation
The correct option is O^2-. O^2- is correct because it directly supports the approved learning objective to use group number to work out the charge on ions from Group 1, Group 2, Group 6 and Group 7 elements. This belongs to the subtopic Ionic bonding within Chemical bonds, ionic, covalent and metallic, so the explanation must stay tied to that curriculum context. The other options are incorrect because they either do not answer this learning objective, use a vague statement, or move away from Ionic bonding.
Common mistake
Misunderstanding Ion Charges
Students often confuse the charges of ions from Group 1 and Group 2 with those from Group 6 and Group 7, leading to incorrect assignments of positive and negative charges.
Remember that Group 1 and Group 2 elements form positive ions by losing electrons, while Group 6 and Group 7 elements form negative ions by gaining electrons. Use the group number to determine the charge: Group 1 ions have a +1 charge, Group 2 ions have a +2 charge, Group 6 ions have a -2 charge, and Group 7 ions have a -1 charge.
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