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Q.
Find the number of valence electrons present in $0.53$ gram of $Na _{2} CO _{3}$.
Some Basic Concepts of Chemistry
Solution:
Total number of valence electron in $Na _{2} CO _{3}$
$=2 \times 8+24=40 $
$ Na ^{+}=8, CO _{3}^{2-}=24$
Number of valence electron in $106 \,g$ of $Na _{2} CO _{3}$
$=40 \times 6.023 \times 10^{23}$
Number of valence electron in $0.53\, g$ of $Na _{2} CO _{3}$
$=0.2 \times 6.023 \times 10^{23}=1.2046 \times 10^{23} .$