A-LevelChemistryChemical periodicityOct/Nov 2016Paper 1 Q121 Mark
The graph below shows the variation of the first ionisation energy with proton number for some elements. The letters used are not the usual symbols for the elements. [Figure showing first ionisation energy vs proton number graph with points P, Q, R, S, T, U, V, W, X] Which statement about the elements is correct?
AP and X are in the same period in the Periodic Table.
BThe general increase from Q to X is due to increasing atomic radius.
CThe small decrease from R to S is due to decreased shielding.
DThe small decrease from U to V is due to repulsion between paired electrons.
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The correct answer is D. This question tests the candidate's understanding of chemical periodicity within the Chemistrysyllabus. The examiner's mark scheme requires...
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