Answer: half life
Explanation: Radioactive decay follows first order kinetics and the time required for the decay of a radioactive material is calculated as follows:

t= time required
k= disintegration constant
x= amount of substance left after time t
a= initial amount of substance
when one half of the sample is decayed, one half of the sample remains and t can be represented as 
at
, 


Answer:12 mol
Explanation: both vessels are at the same temp and pressure (and the pressure is low and/or the temperature high).
6.7mol per 1.3L = 6.7/1.3 mol/L
so in 2.33L = 6.7*2.33/1.3 = 12 mol