Question

$1.2\times {10}^{24}$ atoms of iron equals _____ moles

(Atomic number (Z) and atomic mass of Iron, Fe is $26$ and $56$ respectively)

• A. $6$
• B. $5$
• C. $4$
• D. $1.99$

Answer 1

Answer: (D)

$1.99$

For $Fe$ molar mass $=56$ g/mole

$1$ mole $={6.023\times 10}^{23}$atoms

$56$g $={6.023\times 10}^{23}$ atoms

$1$ atom$=\frac{1}{{6.023\times 10}^{23}}$moles.

$1.2\times {10}^{24}$ atoms $=\frac{1.2\times {10}^{24}}{{6.023\times 10}^{23}}$ moles $=1.99$ moles.