To find out the degree of freedom, the correct expression is:

1. $f=\frac{2}{\gamma -1}$

2. $f=\frac{\gamma +1}{2}$

3. $f=\frac{2}{\gamma +1}$

4. $f=\frac{1}{\gamma +1}$

The equation of state for 5g of oxygen at a pressure P and temperature T, when occupying a volume V, will be: (where R is the gas constant)
1. PV = 5 RT
2. PV = (5/2) RT
3. PV = (5/16) RT
4. PV = (5/32) RT