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JEE Advanced levelSingle correct optionDifficulty 3 of 3pt031

Mendeleev predicted an element 'eka-aluminium' with atomic mass near 68 and an oxide of formula . This element and its position in the modern long form table are

  1. Ascandium, group 3, period 4, d-block
  2. Bgallium, group 13, period 4, p-block
  3. Cgermanium, group 14, period 4, p-block
  4. Dindium, group 13, period 5, p-block

Answer: B

Eka-aluminium lies just below aluminium, so it is in period 4 of group 13, with an oxide as expected for three valence electrons. This is gallium (atomic mass about 69.7). Scandium is eka-boron and germanium is eka-silicon.
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