Answer: Option (B) is the correct answer.
Explanation:
According to the given reaction equation, formula to calculate [tex]\Delta n[/tex] is as follows.
[tex]\Delta n[/tex] = coefficients of gaseous products - gaseous reactants
= 1 - 0
= 1
Also we know that,
[tex]K_{p} = K_{c} \times (RT)^{\Delta n}[/tex]
[tex]5.6 \times 10^{-3} = K_{c} \times (0.0821 \times 700)^{1}[/tex]
[tex]K_{c} = 0.097 \times 10^{-3}[/tex]
For the equation, [tex]2HgO(s) \rightarrow 2Hg(l) + O_{2}(g)[/tex]
Activity of solid and liquid = 1
As, [tex]K_{p} = \frac{P^{2}_{Hg} \times P_{O_{2}}}{P^{2}_{HgO}}[/tex]
[tex]5.6 \times 10^{-3} = P_{O_{2}}[/tex]
Hence, [tex]P_{O_{2}}[/tex] = 0.0056 atm
Thus, we can conclude that partial pressure of oxygen gas at equilibrium is 0.0056 atm.