factors? a) 2 b) 6 c) 12 d) 3 e) 9 4. A first-order reaction is 40.% complete at the end of 50 . minutes. What is the value of the rate constant (in min 1 )? a) 1.8102 b) 1.0102 c) 1.2102 d) 8.0103 e) none of these