Answer : The final concentration of
is, 2.9 M
Explanation :
Expression for rate law for first order kinetics is given by:

where,
k = rate constant = 
t = time passed by the sample = 3.5 min
a = initial concentration of the reactant = 3.0 M
a - x = concentration left after decay process = ?
Now put all the given values in above equation, we get


Thus, the final concentration of
is, 2.9 M
The processes for the 3 types of weathering are,
biological: rocks worn down by plants
physical: water freezing and thawing in cracks of rocks
chemical: Acid rain
Hope this helped!!
The temperature decreases because there is no ozone in the mesosphere and the amount of air is decreasing.
Mass / volume = density
30.943g / 35ml = 0.88408571g/ml