Question

How many grams of sodium will have the same number of atoms as 6 g of magnesium?

$(Na=23,Mg=24)$

Answer 1

Atomic mass of $Mg=24g=1$ mole of $Mg$

$\therefore$ $24g$ $=1$ mole of $Mg$ contain $6.022\times {10}^{23}$ atom

$\therefore$ $6gm$ contains $\frac{6.022\times {10}^{23}}{24}\times 6$

$=4\times 6.022\times {10}^{23}$ atoms

Now according to question, there are $6.022\times {10}^{23}$ atoms of $Na$

$23gm$ of $Na$ contains $6.022\times {10}^{23}$ atoms

$\therefore 6.022\times 4\times {10}^{23}$ atoms of $Na$ weighs $\frac{23\times 6.022\times {10}^{23}\times 4}{6.022\times {10}^{23}}$$\Rightarrow 92gm$