How many moles of ions are in 26.5 g of MgCl2?

In both solid and liquid states, each mole of MgCl₂ contains 1 mole of Mg²⁺ ions and 2 moles of Cl⁻ ions, i.e. 3 moles of ions.
(In solid state, the ions are well arranged in pattern. In liquid state, the ions are mobile.)

Molar mass of MgCl₂ = (24.3 + 35.5×2) g/mol = 95.3 g/mol
No. of moles of MgCl₂ = (26.5 g) / (95.3 g/mol) = 0.278 mol
No. of moles of ions = (0.278 mol) × 3 = 0.834 mol

====
OR:
(26.5 g MgCl₂) × (1 mol MgCl₂ / 95.3 g MgCl₂) × (3 mol ions / 1 mol MgCl₂)
= 0.834 mol ions

zero. no ions form until it is dissolved in water. Magnesium chloride is a white solid.