89. Calculate the pH of a 10M solution of Ba(OH)2 if it undergoes complete ionisation. (K = 1 x 1014) - (1) 12.30 (3) 10.00 (2) 11.30 (4) 9.00 90. Which of the following has maximum solubility (Ksp value is given in brackets) :- (1) HgS (1.6 x 10-54) (2) PbSO4 (1.3 x 10-) (3) ZnS (7.0 1026) (4) AgCl (1.7 x 10-10) 91. Two substance A(t1/2 = 5 min) and B(t1/2 = 15 min) follow first order kinetics are taken in such way that initially [A] = 4[B] then time after which the concentration of both the substance will be equal :- (1) 20 min (3) 50 min (2) 5 min (4) 15 min 92. Rate constant for a chemical reaction at 300 k is expressed as k A e 200, then activation energy of reaction is - (1) 200 kcal/mol (2) 120 cal/mol (3) 120 kcal/mol (4) 300 cal/mol