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Formula of a compound from the fraction of tetrahedral or octahedral voids its atoms occupy

This type of question, asked 10 times: 15 May 2023 S1, 15 May 2023 S2, 14 May 2024 S1, 19 Apr 2025 S2, 13 Apr 2026 S2, 19 Apr 2026 S2, 12 May 2026 S1, 13 May 2026 S1, 14 May 2026 S2, 15 May 2026 S1. All 10 questions below, oldest first.

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  1. Question 1

    15 May 2023 S1

    97
    A compound is formed by two elements A and B. The atoms of element B form ccp structure. The atoms of A occupy 13\frac{1}{3} of tetrahedral voids. What is the formula of the compound?

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  2. Question 2

    15 May 2023 S2

    59
    In a solid, B−B^- ions occupy corners of a cube forming ccp structure. If A+A^+ ion occupy half the tetrahedral voids, formula of the solid is

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  3. Question 3

    14 May 2024 S1

    56
    In an ionic crystalline solid atoms of element Y form hcp structure. The atoms of element X occupy one third of tetrahedral voids. What is the formula of compound?

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  4. Question 4

    19 Apr 2025 S2

    82
    In ionic solid, anions are arranged in ccp array and cations occupy 1/31/3 tetrahedral voids. What is the formula of ionic compound? [Consider A=A = cation; B=B = anion]

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  5. Question 5

    13 Apr 2026 S2

    18
    An ionic compound is formed by elements X and Y. Element Y forms a face-centered cubic (FCC) lattice, and element X occupies one-third of the tetrahedral voids. What is the formula of the compound?

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  6. Question 6

    19 Apr 2026 S2

    26
    In ionic solid, anions are arranged in hcp array and cations occupy 12\dfrac{1}{2} tetrahedral voids. What is the formula of ionic compound ? [Consider A = Cation ; B = anion]

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  7. Question 7

    12 May 2026 S1

    17
    A compound is formed by two elements A and B. The elements B forms cubic close packed structure and atoms of A occupy 1/31/3rd of tetrahedral voids. If the formula of the compound is AxByA_xB_y, then find the value of (x+y)(x + y).

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  8. Question 8

    13 May 2026 S1

    20
    A compound is formed by two elements X and Y, atoms of the element Y as anion make ccp and those of the element X as cation occupy all the octahedral voids. What is the formula of the compound ?

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  9. Question 9

    14 May 2026 S2

    18
    The compound is formed of two different elements A and B. Atoms of B forms hcp structure and atoms of A occupy 2/3rd of octahedral voids. Calculate the formula of compound.

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  10. Question 10

    15 May 2026 S1

    18
    In a solid, oxide ions are arranged in ccp. Cation A occupies 1/81/8th of the tetrahedral voids and cation B occupies 1/41/4th of the octahedral voids. What is the formula of the compound?

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