Answer is: 0,014 moles of PbCl₄ are needed.
Chemical dissociation: PbCl₄ → Pb⁴⁺ + 4Cl⁻.
m(Cl⁻) = 2,00 g.
n(Cl⁻) = m(Cl⁻) ÷ M(Cl⁻).
n(Cl⁻) = 2 g ÷ 35,45 g/mol.
n(Cl⁻) = 0,056 mol.
From chemical reaction: n(Cl⁻) : n(PbCl₄) = 4 : 1.
n(PbCl₄) = 0,056 mol ÷ 4.
n(PbCl₄) = 0,014 mol = 1,4·10⁻² mol.
