If the unit cell of a mineral has cubic close packed (ccp) array of oxygen atoms with m fraction of octahedral holes occupied by aluminium ions and n fraction tetrahedral holes occupied by magnesium ions, m and n, respectively, are -

Question

If the unit cell of a mineral has cubic close packed (ccp) array of oxygen atoms with m fraction of octahedral holes occupied by aluminium ions and n fraction tetrahedral holes occupied by magnesium ions, m and n, respectively, are - (A) (1/2), (1/8) (B) 1, (1/4) (C) (1/2), (1/2) (D) (1/4), (1/8)

Tardigrade Admin · Accepted Answer

T.V. O.V. c.c.p. Mg2+ Al3+ O2- 8n 4m 4 â´ 8n Ã (+2) + 4m Ã (+3) + 4 Ã (-2) = 0 On verifying option, we get n = (1/8), m = (1/2)

Q. If the unit cell of a mineral has cubic close packed $(cc p)$ array of oxygen atoms with $m$ fraction of octahedral holes occupied by aluminium ions and $n$ fraction tetrahedral holes occupied by magnesium ions, $m$ and $n$ , respectively, are -

$\frac{1}{2}, \frac{1}{8}$

$1, \frac{1}{4}$

$\frac{1}{2}, \frac{1}{2}$

$\frac{1}{4}, \frac{1}{8}$

$T . V . O . V . c . c . p .$
$M g^{2 +} A l^{3 +} O^{2 -}$
$8 n 4 m 4$
$∴ 8 n \times (+ 2) + 4 m \times (+ 3) + 4 \times (- 2) = 0$
On verifying option, we get
$n = \frac{1}{8}, m = \frac{1}{2}$

Q. If the unit cell of a mineral has cubic close packed (ccp) array of oxygen atoms with m fraction of octahedral holes occupied by aluminium ions and n fraction tetrahedral holes occupied by magnesium ions, m and n, respectively, are -

21​,81​

1,41​

21​,21​

41​,81​