Mass of lead (II) chromate is 51 g. The molecular formula is [tex]PbCrO_{4}[/tex] and its molar mass is 323.2 g/mol
Number of moles can be calculated using the following formula:
[tex]n=\frac{m}{M}[/tex]
Here, m is mass and M is molar mass.
Putting the values,
[tex]n=\frac{(51 g}{323.1937 g/mol}=0.1578 mol[/tex]
Therefore, number of moles of lead (II) chromate will be 0.1578 mol.