Solar Energy is the answer
<h2>Answer:</h2><h3>The temperature of the gas: V</h3>
The temperature of gas is a variable quantity. It can be changed by changing energy or pressure of gas.
<h3>The amount of gas in the tube (in terms of mass and moles): C</h3>
It is a constant entity. As mass of gas once taken can not be changed by changing temperature, pressure etc.
<h3>The radius of the tube: C</h3>
The radius of tube cannot change at any rate.
<h3>The temperature of the gas (changed by the water surrounding it): V</h3>
It can be changed by changing the temperature of water surrounding it.
<h3>The type of gas: C</h3>
It can never be changed.
<h3>The pressure of the gas: V</h3>
It can be changed by simply changing temperature and volume of gas.
There are:
19.8g of nuts (90x0.22=19.8)
31.5g of granola (90x0.35=31.5)
16.2g of dried fruit (90x0.18=16.2)
22.5g of chocolate chips (90x0.25=22.5)
Use the formula for second order reaction:

C = concentration at time t
C0 = initial conc.
k = rate constant
t = time
1st equation :

2nd Equation:

Find

from 1st equation and put it in 2nd equation:


k = 0.046