Answer:
0.015 M
Step-by-step explanation:
For a first order reaction;
ln[A] =ln[A]o - kt
[A] = final concentration
[A]o =initial concentration
k= rate constant
t= time taken
ln[A] =ln[A]o - kt
ln[A] = ln(0.0500) - 6.7 x 10-4 (30 × 60)
ln[A] = -2.9957 - 1.206
ln[A] = -4.202
e^ln[A] = e^(-4.202)
A= 0.015 M