They are found in group 3 of the periodic table.
The volume of one mole of any gas at Standard Temperature and Pressure (1 atm and 0 degrees Celsius [273K]) is 22.4 L.
Answer: P₂=0.44 atm
Explanation:
For this problem, we are dealing with temperature and pressure. We will need to use Gay-Lussac's Law.
Gay-Lussac's Law: 
First, let's do some conversions. Anytime we deal with the Ideal Gas Law and the different laws, we need to make sure our temperature is in Kelvins. Since T₂ is 64°C, we must change it to K.
64+273K=337K
Now, it may be uncomfortable to use kPa instead of atm, so let's convert kPa to atm.

Since our units are in atm and K, we can use Gay-Lussac's Law to find P₂.


P₂=0.44 atm
We have as a reagent a salt, lead nitrate (Pb(NO3)2), and an unknown solution that gives us as a product lead chloride (PbCl2). That is, the solution must contain chlorine.
If a chlorine solution is used we will have the following reaction:

So, with a chlorine solution, we will have a white precipitate of lead chloride.