The given concentration of boric acid = 0.0500 M
Required volume of the solution = 2 L
Molarity is the moles of solute present per liter solution. So 0.0500 M boric acid has 0.0500 mol boric acid present in 1 L solution.
Calculating the moles of 0.0500 M boric acid present in 2 L solution:

Converting moles of boric acid to mass:

Therefore, 6.183 g boric acid when dissolved and made up to 2 L with distilled water gives 0.0500 M solution.
Meta oxides are compounds that are formed by reaction of metals with oxygen. If these compounds are placed in water, the ionic components of this substance will dissociate.
The dissociation of metal oxides in water will likely form,
2M³⁺ + 3O²⁻
% yield = 80.719
<h3>Further explanation</h3>
Given
22.0 g of Mgl₂
25.0 g of Mg
25.0 g of l₂
Required
The percent yield
Solution
Reaction
Mg + I₂⇒ MgI₂
mol Mg = 25 g : 24.305 g/mol = 1.029
mol I₂ = 25 g : 253.809 g/mol = 0.098
Limiting reactant = I₂
Excess reactant = Mg
mol MgI₂ based on I₂, so mol MgI₂ = 0.098
Mass MgI₂ (theoretical):
= mol x MW
= 0.098 x 278.114
= 27.255 g
% yield = (actual/theoretical) x 100%
% yield = (22 / 27.255) x 100%
% yield = 80.719
Answer : The enthalpy change during the reaction is -6.48 kJ/mole
Explanation :
First we have to calculate the heat gained by the reaction.

where,
q = heat gained = ?
m = mass of water = 100 g
c = specific heat = 
= final temperature = 
= initial temperature = 
Now put all the given values in the above formula, we get:


Now we have to calculate the enthalpy change during the reaction.

where,
= enthalpy change = ?
q = heat gained = 23.4 kJ
n = number of moles barium chloride = 

Therefore, the enthalpy change during the reaction is -6.48 kJ/mole
The new volume at standard pressure of 1 atm is 21294 liters.
Explanation:
Data given:
Initial volume of the gas V1 = 338 liters
initial pressure on the gas P1 = 63 atm
standard pressure as P2 = 1 atm
Final volume at standard pressure V2 =?
The data given shows that Boyle's law equation is to used:
P1V1 = P2V2
rearranging the equation to calculate V2,
V2 = 
Putting the values in the equation:
V2 = 
= 21294 L
as the pressure on the gas is reduced to 1 atm the volume of the gas increased incredibly to 21294 litres.