<u>Answer:</u>
<u>For a:</u> The partial pressure of oxygen gas at equilibrium is 
<u>For b:</u> The reaction must proceed in the forward direction to reach equilibrium.
<u>For c:</u> The value of
is 
<u>Explanation:</u>
For the given chemical equation:

In the expression of
, the partial pressures of solids and liquids are taken as 1.
The expression of
for above equation follows:

We are given:

Putting values in above equation, we get:

Hence, the partial pressure of oxygen gas at equilibrium is 
is the constant of a certain reaction at equilibrium while
is the quotient of activities of products and reactants at any stage other than equilibrium of a reaction.
The expression of
for above equation follows:

We are given:

Putting values in above equation, we get:

There are 3 conditions:
- When
; the reaction is product favored. - When
; the reaction is reactant favored. - When
; the reaction is in equilibrium.
As,
, the reaction will be favoring product side.
Hence, the reaction must proceed in the forward direction to reach equilibrium.
Relation of
with
is given by the formula:

Where,
= equilibrium constant in terms of partial pressure = 
= equilibrium constant in terms of concentration = ?
R = Gas constant = 
T = temperature = 298 K
= change in number of moles of gas particles = 
Putting values in above equation, we get:

Hence, the value of
is 