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 were based on atomic mass only
- B. They did not include all known elements
- C. They lacked noble gases
- D. They were arranged randomly
Answer
The correct option is They were based on atomic mass only.
Explanation
The correct option is They were based on atomic mass only. They were based on atomic mass only is correct because it directly supports the approved learning objective to describe how elements are arranged in order of atomic number in the modern periodic table. This is tested in the subtopic 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 The periodic table precisely. Repair marker d438d213 keeps this question distinct from adjacent atom, ion, isotope, group, period, and electronic-structure questions.
Common mistake
Misunderstanding Atomic Number Arrangement
Students often think elements are arranged by atomic mass instead of atomic number in the periodic table.
Remember that the modern periodic table arranges elements in order of increasing atomic number, which is the number of protons in the nucleus.
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