Q.
[A]0/mol L-1 t1/2/min
0.100 200
0.025 100


For a given reaction RP, t1/2 is related to [A]0 as given in the table.
Given: log 2 = 0.30

Which of the following is true 

(A)  The order of the reaction is 1/2.

(B)  If [A]0 is 1 M, then t1/2 is 20010 min.

(C)  The order of the reaction changes to 1 if the concentration of reactant changes from 0.100 M to 0.500 M.

(D)  t1/2 is 800 min for [A]0 = 1.6 M.

Choose the correct answer from the options given below:                  [2025]

1 (C) and (D) Only  
2 (A) and (B) Only  
3 (A), (B) and (D) Only  
4 (A) and (C) Only  

Ans.

(3)

(A) For nth order reaction, t1/2 is related to initial concentration (a0) as:

t1/2a01-n

(t1/2)1(t1/2)2=((a0)1(a0)2)1-n

200100=(0.100.025)1-n

2=41-n

n=12

(B)  (t1/2)for a0=1M(t1/2)1=(1(a0)1)1-n

(t1/2)for a0=1M200=(10.1)1-12

(t1/2)for a0=1M=20010 min

(D) (t1/2)for a0=1.6M(t1/2)1=(1.6(a0)1)1-n

(t1/2)for a0=1.6M200=(1.60.1)1-12

(t1/2)for a0=1.6M=800 min