Answer is (4) - Se.
Among the given choices Se has the highest electronegativity value as 2.4 compared to others. Hence, Se shows <span>greatest attraction for electrons in a chemical bond.
</span>Electronegativity is
a value that tells us how an atom can attract electrons towards itself. <span>If
the electronegativity is high, then the attraction to the electrons is also high.
</span>
Complete Question
You determine that it takes 26.0 mL of base to neutralize a sample of your unknown acid solution. The pH of the solution was 7.82 when exactly 13 mL of base had been added, you notice that the concentration of the unknown acid was 0.1 M. What is the pKa of your unknown acid?
Answer:
The pK_a value is
Explanation:
From the question we are told
The volume of base is 
The pH of solution is 
The concentration of the acid is 
From the pH we can see that the titration is between a strong base and a weak acid
Let assume that the the volume of acid is 
Generally the concentration of base

Substituting value


When 13mL of the base is added a buffer is formed
The chemical equation of the reaction is

Now before the reaction the number of mole of base is
![No \ of \ moles[N_B] = C_B * V_B](https://tex.z-dn.net/?f=No%20%5C%20of%20%5C%20moles%5BN_B%5D%20%20%3D%20%20C_B%20%2A%20V_B)
Substituting value

Now before the reaction the number of mole of acid is

Substituting value


Now after the reaction the number of moles of base is zero i.e has been used up
this mathematically represented as

The number of moles of acid is


The pH of this reaction can be mathematically represented as
![pH = pK_a + log \frac{[base]}{[acid]}](https://tex.z-dn.net/?f=pH%20%20%3D%20pK_a%20%2B%20log%20%5Cfrac%7B%5Bbase%5D%7D%7B%5Bacid%5D%7D)
Substituting values

Answer:
Option C. PV = nRT
Explanation:
The ideal gas gas equation gives the relationship between pressure, volume, number mole a gas and temperature of gas.
Mathematically, the ideal gas equation is given as:
PV = nRT
Where:
P is the pressure measured in atmosphere (atm).
V is the volume measured in litres(L) or cubic decimetre (dm³).
n is the number of mole of gas.
R is the gas constant (0.0821atm.L/Kmol)
T is temperature measured in Kelvin (K).