Describe tests using aqueous sodium hydroxide and aqueous ammonia to identify the aqueous cations: (a) aluminium, Al^3+ (b) ammonium, NH4^+ (c) calcium, Ca^2+ (d) chromium(III), Cr^3+ (e) copper(II), Cu^2+ (f) iron(II), Fe^2+ (g) iron(III), Fe^3+ (h) zinc, Zn^2+

State the symbol equation for the production of ammonia in the Haber process, N2(g) + 3H2(g) ⇌ 2NH3(g)