PH is the test of acidity or basicity of a solution. it follows the formula:
pH = pKa + log [salt] / [acid] where NaF is the salt and HF is the acid in this case.
By literature, Ka of HF is 3.5*10^-4
<span>pKa= -log(Ka)=</span><span> 3.46 </span>
<span>pH = pKa + log [NaF / [HF] </span>
4.05 = 3.46 + log [NaF / [HF]
log [NaF / [HF]<span> = 0.59
</span>
[NaF / [HF] = 3.89
Explanation:
As per Brønsted-Lowry concept of acids and bases, chemical species which donate proton are called Brønsted-Lowry acids.
The chemical species which accept proton are called Brønsted-Lowry base.
(a) 
is Bronsted lowry acid and
is its conjugate base.
is Bronsted lowry base and
is its conjugate acid.
(b)

is Bronsted lowry base and HCN is its conjugate acid.
is Bronsted lowry acid and
is its conjugate base.
(c)

is Bronsted lowry acid and
is its conjugate base.
Cl^- is Bronsted lowry base and HCl is its conjugate acid.
(d)

is Bronsted lowry acid and
is its conjugate base.
OH^- is Bronsted lowry base and
is its conjugate acid.
(e)

is Bronsted lowry base and OH- is its conjugate acid.
is Bronsted lowry acid and OH- is its conjugate base.
Mass of CO₂ evolved : 0.108 g
<h3>Further explanation</h3>
Given
1.205g sample, 36% MgCO3 and 44% K2CO3
Required
mass of CO2
Solution
0.36 x 1.205 g=0.4338 g
mass C in MgCO₃(MW MgCO₃=84 g/mol, Ar C = 12/gmol)
= (12/84) x 0.4338
= 0.062 g
0.44 x 1.205 g = 0.5302 g
Mass C in K₂CO₃(MW=138 g/mol) :
= (12/138) x 0.5302
= 0.046 g
Total mass Of CO₂ :
= 0.062 + 0.046
= 0.108 g
<span>It is the valence orbit that controls the electrical properties of the atom. The valence electron is referred to as a "free electron.' Valence electrons have the highest energy of all electrons in an atom; they are also the most reactive, meaning they are usually the electrons involved in bonding. When silicon atoms combine to form a solid, they arrange themselves into an orderly pattern called a crystal.</span>