The question is incomplete, here is a complete question.
An arctic weather balloon is filled with 27.8 L of helium gas inside a prep shed. The temperature inside the shed is 13 ⁰C. The balloon is then taken outside, where the temperature is -9 ⁰C. Calculate the new volume of the balloon. You may assume the pressure on the balloon stays constant at exactly 1 atm. Be sure your answer has the correct number of significant digits.
Answer : The new volume of the balloon is 25.7 L
Explanation :
Charles's Law : It is defined as the volume of the gas is directly proportional to the temperature of the gas at constant pressure and number of moles.

or,

where,
= initial volume of gas = 27.8 L
= final volume of gas = ?
= initial temperature of gas = 
= final temperature of gas = 
Now put all the given values in the above equation, we get:


Therefore, the new volume of the balloon is 25.7 L
Hello!
First, we need to determine the pKa of the base. It can be found applying the following equation:

Now, we can apply the
Henderson-Hasselbach's equation in the following way:
![pH=pKa+log( \frac{[CH_3NH_2]}{[CH_3NH_3Cl]} )=10,65+log( \frac{0,18M}{0,73M} )=10,04](https://tex.z-dn.net/?f=pH%3DpKa%2Blog%28%20%5Cfrac%7B%5BCH_3NH_2%5D%7D%7B%5BCH_3NH_3Cl%5D%7D%20%29%3D10%2C65%2Blog%28%20%5Cfrac%7B0%2C18M%7D%7B0%2C73M%7D%20%29%3D10%2C04)
So,
the pH of this buffer solution is 10,04Have a nice day!
It creates oxygen which every living thing needs to live. i hope this helps! :)