Elements A, B, and C have the following relationships. B is in the same group as A and B's period number is more than A's. C is in
B and C's atomic number is less than B's. The relationship of their electronegativity is:
OB OA OB OC O A

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Explanation:

Mass = 19.53 g

Explanation:

Given data:

Number of atoms of iron = 2.10 ×10²³ atoms

Mass of iron = ?

Solution:

The number 6.022 ×10²³ is called Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.

1 mole contain 6.022 ×10²³ atoms

2.10 × 10²³ atoms ×  1 mol / 6.022 ×10²³ atoms

0.35 mol

Mass of iron atoms:

Mass = Number of moles × molar mass

Mass = 0.35 mol × 55.8 g/mol

Mass = 19.53 g