Q19 / 160 · TS EAMCET 2023 (13 May Shift 1) · Chemistry

A body centred cubic lattice is made up of two different types of atoms X and Y. Atom X occupies the body centre and atoms $\mathrm{Y}$ occupy the corner positions. One of the corners is left unoccupied per unit cell. The empirical formula of it is

  • A
    $\mathrm{X}_2 \mathrm{Y}_3$
  • Correct answer
    B
    $\mathrm{X}_8 \mathrm{Y}_7$
  • C
    $\mathrm{X}_7 \mathrm{Y}_8$
  • D
    $\mathrm{X}_5 \mathrm{Y}_7$

Solution

No. of X atoms per unit cell $=1 \times 8=8$ No. of $Y$ atoms per unit cell $=\left[\left(8 \times \frac{1}{8}\right) \times 8\right]-1=7$ $\Rightarrow$ Empirical formula $=\mathrm{X}_8 \mathrm{Y}_7$

Hence, the correct answer is option: 'B'.

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