Periodic Classification of Elements — Science STD 10 — Question
CBSE BoardEnglish MediumSTD 10SciencePeriodic Classification of Elements1 Mark
MCQ
The element with the atomic number $9$ resembles with the element having the atomic number :
A
$8$
✓
$17$
C
$36$
D
$27$
✓
Answer
Correct option: B.
$17$
Atomic number $9$ has electronic configuration $= 2, 7$
Atomic number $17$ has an electronic configuration $= 2, 8, 7.$
So, both the elements belong to the same group
i.e. halogens and have similar properties as they have the same number of valence electrons.
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