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Molar mass of an element (or mass of unit cells) from its density and unit cell data

This type of question, asked 13 times: 4 May 2023 S1, 9 May 2023 S2, 11 May 2023 S2, 9 May 2024 S2, 10 May 2024 S1, 11 May 2024 S1, 11 May 2024 S2, 12 May 2024 S1, 20 Apr 2025 S1, 11 Apr 2026 S2, 15 Apr 2026 S1, 15 May 2026 S1, 15 May 2026 S2. All 13 questions below, oldest first.

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  1. Question 1

    4 May 2023 S1

    63
    Calculate molar mass of an element having density 8.6 g cm−38.6\text{ g cm}^{-3} if it forms bcc structure a3×NA=22.0 cm3 mol−1a^3 \times N_A = 22.0\text{ cm}^3\text{ mol}^{-1}

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  2. Question 2

    9 May 2023 S2

    51
    Calculate the molar mass of an element having density 5.6 g cm−3^{-3} that forms bcc structure. a3×NA=75a^3 \times N_A = 75 cm3^3 mol−1^{-1}

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  3. Question 3

    11 May 2023 S2

    97
    A metal crystallises in bcc structure with edge length 4×10−84\times10^{-8} cm. If density of unit cell is 10 g cm−310\ \text{g cm}^{-3}. What is its molar mass?

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  4. Question 4

    9 May 2024 S2

    96
    Calculate the molar mass of an element having density 2121 g cm−3^{-3} that forms fcc unit cell, a3⋅NA=36a^3 \cdot N_A = 36 cm³ mol−1^{-1}.

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  5. Question 5

    10 May 2024 S1

    79
    Molar mass of element: density 2.7 g/cm3^3, fcc structure, a3NA=40a^3N_A=40 cm3^3/mol.

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  6. Question 6

    11 May 2024 S1

    83
    What is atomic mass of an element with BCC structure and density 10 g cm−3^{-3} having edge length 300 pm?

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  7. Question 7

    11 May 2024 S2

    65
    Calculate the molar mass of metal having density 9.3 g cm−39.3\ \text{g cm}^{-3} that forms simple cubic unit cell. [a3⋅NA=22.6 cm3 mol−1][a^3 \cdot N_A = 22.6\ \text{cm}^3\ \text{mol}^{-1}]

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  8. Question 8

    12 May 2024 S1

    58
    Calculate the molar mass of an element having density 7.8 g cm−37.8\,\text{g cm}^{-3} that forms bcc unit cell. [a3⋅NA=16.2 cm3 mol−1][a^3\cdot N_A = 16.2\,\text{cm}^3\,\text{mol}^{-1}]

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  9. Question 9

    20 Apr 2025 S1

    98
    Calculate the molar mass of an element if it forms fcc unit cell structure [mass of unit cell =1.8×10−22 g, NA=6.022×1023 mol−1= 1.8 \times10^{- 22}\text{ }g,{\text{ }N}_{A}= 6.022 \times10^{23}{\text{ }mol}^{- 1} ]

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  10. Question 10

    11 Apr 2026 S2

    19
    A compound forms bcc unit cell with edge length 400400 pm. Determine the molar mass of the compound if the density of compound is 3.5 g cm−33.5\ \mathrm{g\,cm^{-3}} [NA=6.022×1023][N_A = 6.022 \times 10^{23}]

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  11. Question 11

    15 Apr 2026 S1

    18
    An element crystallises in fcc unit cell with cell edge length of 3.608×10−83.608 \times 10^{-8} cm, the density of element is 8.92 gcm−38.92\ \mathrm{gcm^{-3}}. Calculate the atomic mass of element (NA=6.022×1023)(\mathrm{N}_A = 6.022 \times 10^{23}).

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  12. Question 12

    15 May 2026 S1

    17
    What is the mass of 5 unit cells of sodium element having bcc structure (molar mass of Na=23\mathrm{Na} = 23 g/mol)?

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  13. Question 13

    15 May 2026 S2

    18
    Calculate the molar mass of a metal having density 10 g cm−310\ \mathrm{g\ cm^{-3}} and fcc structure with edge length 400400 pm.

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