Question

What is the number of oxygen atoms in $0.50$ mole of $A{l}_2(C{O}_3{)}_3$ ?

• A. $4.5\times {10}^{23}$
• B. $9.0\times {10}^{23}$
• C. $3.6\times {10}^{24}$
• D. $2.7\times {10}^{24}$
• E. $5.4\times {10}^{24}$

Answer 1

The correct option is D $2.7\times {10}^{24}$

1 mole of $A{l}_2(C{O}_3{)}_3$ contains $3\times 3=9$ moles of oxygen atoms.
0.5 mole of $A{l}_2(C{O}_3{)}_3$ will contain $0.5\times 9=4.5$ moles of oxygen atoms
1 mole of oxygen atoms corresponds to $6.023\times {10}^{23}$ atoms.
4.5 moles of atoms corresponds to $4.5\times 6.023\times {10}^{23}=2.7\times {10}^{24}$.