Question detail

Why was Mendeleev's periodic table significant?

Try the question, check the answer, then read the explanation to understand the curriculum point.

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At a glance

MCQ

Type

practice

Style

Topic

The periodic table

Question

A. It predicted the existence of undiscovered elements based on properties.
B. It arranged elements by increasing atomic weight without considering properties.
C. It classified all known elements as metals only.
D. It ignored the concept of isotopes.

Answer

The correct option is It predicted the existence of undiscovered elements based on properties..

Explanation

The correct option is It predicted the existence of undiscovered elements based on properties.. It predicted the existence of undiscovered elements based on properties. is correct because it directly supports the approved learning objective to explain how knowledge of isotopes helped explain why atomic weight order was not always correct. 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 8803f1be keeps this question distinct from adjacent atom, ion, isotope, group, period, and electronic-structure questions.

Common mistake

Misunderstanding Isotopes

Students often think that isotopes have different atomic numbers, leading to confusion about atomic weight order.

Remember that isotopes have the same atomic number (protons) but different mass numbers (neutrons). This helps explain why atomic weight order can vary.

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