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Periodic Classification of Elements — Science STD 10 — Question

CBSE BoardEnglish MediumSTD 10SciencePeriodic Classification of Elements5 Marks
Question
Mendeleev predicted the existence of certain elements not known at that time and named two of them as eka - aluminium, and eka - silicon.
  1. Name the element which has taken the place of (i) eka - aluminium, and (ii) eka - silicon.
  2. Mention the period/ periods of these elements in the modern periodic table.
  3. Write the group/ groups of these elements in the modern periodic table.
  4. Classify these elements as metals, non - metals or metalloids.
  5. How many valence electrons are present in the atoms of each of these elements?​​​​​​
✓

Answer

  1.  
  1. Gallium.
  2. Germanium.
  1. 4th period.
  2. Gallium: 13th group; Germanium: 14th group.
  3. Gallium: Metal; Germanium: Metalloid.
  4. Gallium: 3; Germanium: 4.

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