By Avogadro's number, the mass is 1.12 x 10¯²⁰ gram.
We need to know about Avogadro's number to solve this problem. Avogadro's number is the number that explains how many atoms are in one mol. The Avogadro's number is
Na = 6,02 × 10²³ atoms / mol
From the question above, we know that
N = 172 atoms
Ar = 39.1
By using Avogadro's number, we can calculate the amount of potassium
N = Na . n
172 = 6,02 × 10²³ . n
n = 2.86 x 10¯²² mol
Find the mass
n = gr / Ar
2.86 x 10¯²² = gr / 39.1
gr = 1.12 x 10¯²⁰ gram
For more on Avogadro's number at: https://brainly.com/question/1581342
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