It take 42 min for the concentration of a reactant in a first order reaction to drop from 0,45 mol/l to 0,32 mol/l at 25 °C. How long will it take for the reaction to be 90% complete ? A) 130 min
B) 86 min
C) 137 min
D) 284 min

i want the explanation please

What is the number of atoms in 3.54 mol s

Zoe is investigating the composition of substance a, an unknown substance. using chemical processes, she analyzes substance a and determines it is composed of sodium, oxygen, and hydrogen atoms in a ratio of 1 : 1 : 1. what is substance a? a. a compound b. an element c. a heterogeneous mixture d. a homogeneous mixture

Which are forms of frozen water? check all that apply. dew frost hail rain sleet