For the given cell; Cu(s)|cu²⁺ (C1M)||Cu²⁺(C₂M)|Cu(s) Change in Gibbs energy (ΔG) is negative, if :
(1) C₁ = 2C₂
(2) C₂ = C₁/ √2
(3) C₁ = C₂
(4) C₂ = √2 C₁