Question

the sample which doesn't contain same number of sodium atoms as there are sodium atom in 5.3g of na2co3 is​

Answer 1

Molar mass :-

$\\ \sf\longmapsto Na_2CO_3$

$\\ \sf\longmapsto 2(23u)+12u+3(16u)$

$\\ \sf\longmapsto 46u+12u+48u$

$\\ \sf\longmapsto 106u$

$\\ \sf\longmapsto 106g/mol$

• Given mass=5.3g

$\boxed{\sf No\:of\:moles =\dfrac{Given\:mass}{Molar\:mass}}$

$\\ \sf\longmapsto No\:of\:moles=\dfrac{5.3}{106}$

$\\ \sf\longmapsto No\:of\:moles=0.05mol$

Now

$\boxed{\sf No\:of\;atoms=No\:moles\times Avagadro\:no}$

$\\ \sf\longmapsto No\:of\:atoms=0.05\times 6.023\times 10^{23}$

$\\ \sf\longmapsto No\:of\:atoms=0.3011\times 10^{23}$

$\\ \sf\longmapsto No\:of\:atoms=3.0\times 10^{22}$

Answer 2

$Molar \: \: mass :- \\ \begin{gathered}\\\sf\longmapsto Na_2CO_3\end{gathered} \\ \begin{gathered}\\ \sf\longmapsto 2(23u)+12u+3(16u)\end{gathered} \\ \begin{gathered}\\ \sf\longmapsto 46u+12u+48u\end{gathered} \\ \begin{gathered} \sf\longmapsto 106u\end{gathered} \\ \ \begin{gathered} \sf\longmapsto 106g/mol\end{gathered} \\ \\ Given mass=5.3g \\ \\ \boxed{\sf No\:of\:moles =\dfrac{Given\:mass}{Molar\:mass}} \\ \\ \begin{gathered} \sf\longmapsto No\:of\:moles=\dfrac{5.3}{106}\end{gathered} \\ \\ \begin{gathered} \sf\longmapsto No\:of\:moles=0.05mol\end{gathered} \\ \\ Now \\ \\\boxed{\sf No\:of\;atoms=No\:moles\times Avagadro\:no} \\ \\\begin{gathered \sf\longmapsto No\:of\:atoms=0.05\times 6.023\times 10^{23}\end{gathered} \\ \\ \begin{gathered} \sf\longmapsto No\:of\:atoms=0.3011\times 10^{23}\end{gathered} \\ \\ \begin{gathered} \sf\longmapsto No\:of\:atoms=3.0\times10^{22}\end{gathered}$