(a) Give the pK_b values of the following bases: 

(i) Ammonia, NH₃, K_b = 1.8 * 10^–5; 

(ii) Deuterated ammonia, ND₃, K_b = 1.1 * 10^–5; 

(iii) Hydrazine, NH₂NH₂, K_b = 1.7 * 10^–6; 

(iv) Hydroxylamine, NH₂OH, K_b = 1.1 * 10^–8. 

(b) List the bases in order of increasing strength.