[Single-digit Integer] An iron meteorite was analysed for its isotopic argon content. The amount of Ar^36 was 1.911 mm^3 (STP) per kg of meteorite. If each Ar^36 atom had been formed by a single cosmi

Question

[Single-digit Integer] An iron meteorite was analysed for its isotopic argon content. The amount of Ar^36 was 1.911 mm^3 (STP) per kg of meteorite. If each Ar^36 atom had been formed by a single cosmic event, how many such events must there have been per kg of meteorite? If the answer is X, then the value of X / 10^16 is (R = 8.4 J/K-mol, NA = 6.0 × 10^23)

Prashant Kotian · Accepted Answer

Correct answer: 5. At STP, volume V = 1.911 mm^3 = 1.911 × 10^-6 L. Moles of Ar^36 = 1.911 × 10^-6 / 22.4 = 8.53 × 10^-8 mol. Number of atoms (events) = 8.53 × 10^-8 × 6.022 × 10^23 = 5.13 × 10^16. Thus, X = 5.13 × 10^16. The value of X / 10^16 is ≈ 5. Thus, the integer answer is 0005.

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