Per NCERT §3.3, the PERIOD number in the modern periodic table corresponds to which quantity?
AThe number of valence electrons
BThe atomic number divided by 8
CThe highest principal quantum number n of valence electrons in the period
DThe group number
Answer & Solution
Correct answer: C. The highest principal quantum number n of valence electrons in the period
Per NCERT §3.3, period number = highest principal quantum number n filled by elements in that row.
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