Verified Solution • 2025–26 Session moderate

QJEEM20Cha23a: JEE Main 2020 Chemistry - Class 12 JEEM20Cha23a Solution: A crystal is made up of metal ions 'M 1 ' and 'M 2 ' and oxide…

A crystal is made up of metal ions 'M1' and 'M2' and oxide ions. Oxide ions form a ccp lattice structure. The cation 'M1' occupies 50% of octahedral voids and the cation 'M2' occupies 12.5% of tetrahedral voids of oxide lattice. The oxidation numbers of 'M1' and 'M2' are, respectively :

Multiple Choice Options

  • A + 3, + 1
  • B + 4, + 2
  • C + 1, + 3
  • D + 2, + 4

Step-by-Step Verified Solution

O–2 ions form ccp ⇒\Rightarrow O4.

M1 = 50% octahedral void = 50100×4{{50} \over {100}} \times 4 = 2

M2 = 12.5% tetrahedral void = 12.5100×8{{12.5} \over {100}} \times 8 = 1

So formula is : (M1)2(M2)1O4

Let charge on M1 and M2 are +x and +y respectively. And O4 has -8 charge.

As crystal is neutral. So metals must have +8 charge in total.

∴\therefore +2x + y = 8 ....(1)

By checking options we found eq (1) satisfy when
x = +2
y = +4

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