The moles are the estimation of the quantities like the molecules and the atoms. There are 7.984 moles of aluminum present in the 2.154 × 10⁻¹ kg substance. Thus, option b is correct.
The moles give the estimation of the smaller entities by the ratio of mass or weight to the molar mass of the substance.
The formula for moles is given as,
Moles = mass ÷ molar mass
Given,
Mass of aluminium = 2.154 × 10⁻¹ kg = 2.154 × 10² gm
Molar mass of Al = 26.9 g/mol
Substituting values above:
Moles = 2.154 × 10² gm ÷ 26.9 g/ mol
= 7.984 mol
Therefore, option. 7.984 moles of aluminum are present.
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