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Periodic Classification of Elements — Science STD 10 — Question

CBSE BoardEnglish MediumSTD 10SciencePeriodic Classification of Elements3 Marks
Question
Consider the following elements: ${ }_{20} Ca ,{ }_8 O ,{ }_{18} Ar ,{ }_{16} S,{ }_4 Be ,{ }_2 He$.
Which of the above elements would you expect to be:
i. Very stable?
ii. In group 2 of the periodic table?
iii. In group 16 of the periodic table?
✓

Answer

i. ${ }_{18} Ar$ and ${ }_2 He$ (Noble gases).
ii. ${ }_{20} Ca$ and 4 Be (no. of valence electrons in each $=2$ ).
iii. 8 O and ${ }_{16} S$ (no. of valence electrons in each $=6$ ).

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