(b) Nickel and copper are completely soluble in each other in both liquid and solid states. (i) From Table Q2(b), list FOUR (4) conditions that allow both elements completely soluble in each other. Table Q2(b): Data of copper and nickel Copper (Cu) Nickel (Ni) Atomic radii 0.128 nm 0.125 nm Crystal structure FCC FCC Electronegativity 1.9 1.8 Valence +1, +2 +2 [4 marks] (ii) State whether the solution formed by the two elements is a substitutional solid solution or interstitial solid solution. [1 mark]