$3.2$ g of ferric oxide [${\mathrm{Fe}}_2{\mathrm{O}}_3$] is equivalent to:
$\left[\mathrm{Fe}=56; \mathrm{O}=16\right]$

$0.6$ mol of hydrogen peroxide [${\mathrm{H}}_2{\mathrm{O}}_2$] weighs:        

$\left[\mathrm{H}=1,\mathrm{O}=16\right]$

$0.15$ g mol of ammonia weighs?        

$\left[\mathrm{N}=14; \mathrm{H}=1\right]$

The weight of $1.2$ mol of copper carbonate [${\mathrm{CuCO}}_3$ ] is:

$\left[\mathrm{Cu}=64; \mathrm{C}=12; \mathrm{O}=16\right]$

Number of aluminium ions in $0.056$ g of aluminium oxide is:

$\left[\mathrm{Al}=27; \mathrm{O}=16\right]$

Number of ferric ions in $0.8$ g of ${\mathrm{Fe}}_2{\mathrm{O}}_3$ is:

$\left[\mathrm{Fe}=56; \mathrm{O}=16\right]$

The number of calcium ions in $15.5$ g of ${\mathrm{Ca}}_3({\mathrm{PO}}_4{)}_2$ is:

$\left[\mathrm{Ca}=40; \mathrm{P}=31; \mathrm{O}=16\right]$

The number of atoms in $5.6$ g of nitrogen gas (${\mathrm{N}}_2$) is:     

$\left[\mathrm{N}=14\right]$

The number of atoms in $3.55$ g of chlorine (${\mathrm{Cl}}_2$) is:

$\left[\mathrm{Cl}=35.5\right]$