Answer:
B. 
Explanation:
The unit for rate is M/s while the unit for each molecule should be M. You can find the unit for k by putting the units for rate and the molecules into the equation
rate= k{X][Y]
M/s= k *
* 
k= (M/s) / (
)
k= 
You can also use this predetermined formula to solve this problem faster: k= 
Where n is the number of molecule. There are 3 molecule(2X and 1Y) so n=3, so
k= 
k=
=
= 
This rock is balanced by roots on the ground that are very strong
The molar mass of gas = 238.29 g/mol
<h3>Further explanation</h3>
Given
mass = 81.5 g
P=1.75 atm
V=4.92 L
T=307 K
Required
molar mass
Solution
The gas equation can be written


So the equation becomes :

Input the value :
