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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:
Ca, Cl, Na, I, Li, Ba, Sr, K, Br.
Separate these elements into three groups (families) of similar properties. State one property in each case on the basis of which you have made your choice.
✓

Answer

  1. Lithium (Li), sodium (Na) and potassium (K) are three metals of group 1 having a valency of 1.
  2. Calcium (Ca), strontium (Sr) and barium (Ba) are three metals of group 2 having a valency of 2.
  3. Chlorine (Cl), bromine (Br) and iodine (I) are three non-metals of group 17 which are known as halogens, and have seven valence electrons.

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