Answer:
so rate constant is 4.00 x 10^-4 
Explanation:
Given data
first-order reactions
85% of a sample
changes to propene t = 79.0 min
to find out
rate constant
solution
we know that
first order reaction are
ln [A]/[A]0 = -kt
here [A]0 = 1 and (85%) = 0.85 has change to propene
so that [A] = 1 - 0.85 = 0.15.
that why
[A] / [A]0= 0.15 / 1
[A] / [A]0 = 0.15
here t = (79) × (60s/min) = 4740 s
so
k = - {ln[A]/[A]0} / t
k = -ln 0.15 / 4740
k = 4.00 x 10^-4 
so rate constant is 4.00 x 10^-4 
Answer:
19.1 secs
Explanation:
The first step is to calculate the velocity
= 17.4/47.6
= 0.37 m/s
Therefore the time taken for the person to reach the top can be calculated as follows
= 17.4/(0.37+0.541)
= 17.4 / 0.911
= 19.1 secs
Hence the time taken is 19.1 secs
A. A fast moving stream. Water has erode Earth for thousands of years. This was what caused the Grand Canyon. A faster ,owing stream would cause a faster erosion due to the speed and strength of the water itself.