Question

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Answer 1

$1 \: mol \: = 6.022 \times {10}^{23} atoms$

$no. \: of \: moles \: in \: 42.154 \times {10}^{23} atom \: of \: sodium \: = \frac{42.154 \times {10}^{23} }{6.022 \times {10}^{23} }$

$= 7 \: moles$