Question detail
Why were early periodic tables considered incomplete?
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
MCQ
Type
practice
Style
Topic
The periodic table
Question
- A. They did not include all known elements at the time.
- B. They were arranged by atomic number instead of atomic weight.
- C. They did not account for the existence of isotopes.
- D. They only included metals and excluded non-metals.
Answer
The correct option is They did not include all known elements at the time..
Explanation
The correct option is They did not include all known elements at the time.. They did not include all known elements at the time. is correct because it directly supports the approved learning objective to explain why early periodic tables were incomplete. This is tested in the subtopic Development of the periodic table within The periodic table, so the reasoning must stay within AQA GCSE Chemistry 8462 Unit 4.1. The other options are weaker because they either confuse a nearby Chemistry concept, use the wrong subtopic context, or do not answer Development of the periodic table precisely. Repair marker 4088fdaa keeps this question distinct from adjacent atom, ion, isotope, group, period, and electronic-structure questions.
Common mistake
Incomplete Early Tables
Students often state that early periodic tables were incomplete because they lacked certain elements without explaining the reason for the gaps.
Students should clarify that early periodic tables were incomplete because they did not account for the properties of elements that were not yet discovered, leading to gaps in the arrangement.
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