James CHadwick discovered the subatomic particles caled neutrons
According to the second-order rate constant formula:
K t = 1/[At] - 1/[Ao]
when k is the rate constant = 0.035 (given missing in your question)
and t is the time = 190 sec
Ao is the initial concentration of X = 0.35 m
by substitution:
0.035 * 190 sec = 1/[At] - 1/0.35
∴ [At] = 0.11 m
∴ the concentration after 190 sec = 0.11 m
D.It can not be separated by a physical change.
