Question

How many number of aluminium ions are present in $0.051g$ of aluminium oxide?

• A. $6.023\times 10^{20}$ ions
• B. $3$ ions
• C. $6.023\times 10^{23}$ ions
• D. $9$ ions

Answer 1

Answer: (A)

Mass of $A{l}_2{O}_3=2\times 27+3\times 16=102$
$0.051g$ of $A{l}_2{O}_3=\frac{0.051}{102}=0.0005$ mol
$1$ mol of $A{l}_2{O}_3$ contains $2\times 6.023\times 10^{23}A{l}^{3+}$ ions
$0.0005$ mol of $A{l}_2{O}_3$ contains $2\times 6.023\times 6.023\times 10^{23}$
$A{l}^{3+}$ ions $=6.023\times 10^{20}A{l}^{3+}$ ions