Element atomic number position
Ba 56 group 2, period 6
Ca 12 group 2, period 3
S 16 group 16, period 3
Si `14 group 14, period 3
Now, you need to know the properties of the different type of elements and the tendencies on the periodic table.
The metallic elements are, those placed on the left side of the periodic table, are the ones that release an electron more easily, so they will requiere less energy to give it up when forming chemical bonds.
The higher the metallic character the less the energy need to give up an electron.
The metallic character grows as the group number decreases (goes to the left) period increases (goes downward), so among the elements considered, Barium will require the least amount of energy to give un an electron when forming chemical bonds.
We are going to apply the equation of state for ideal gasses: P*V = n*R*T where P is pressure, V is volum, n is mols of gas, T is temperature and R is a constant value of 0.082 (atm*l)/(mol*K)
We know the temperature is 45 ÂşC so in Kelvins will be = 45 + 273.16 = 318.16 K
Then in the equation:
V = n*R*T/P = 1.5 * 0.082 * 318.16 / 2.5 = 15.65 l
So volum of gas is: 15.65 liters
Initially, weigh the correct amount of 
calculated from the formula.
Number of moles =
As 1 mole of is given and molar mass of is 
, then
1 mole of = 
Mass of in g = 
Thus,
1 mole of = 58.44 g.
Now, the weighed amount of i.e. 58.44 g is added to a 1 liter container and then add small amount of water in the container to dissolve the salt. After that, fill the container with distilled water to the graduation mark or until the total volume reaches 1 liter.
Thus, option (c) is correct i.e. first put one mole of salt in the container then add the water with stirring till the total volume reaches 1 liter.
