Answer: 5. high temperatures and low pressures.
Step-by-step explanation:
Real gases are the gases whose molecules have considerable volume and they occupy large space.
Whereas molecules of ideal gas have negligible volume as compared to the total volume and therefore, they do not occupy any space.
A real gas behave like an ideal gas under the conditions of high temperature and low pressure.
This is because at high temperature and low pressure molecules of gas will have high kinetic energy , and will be far part and weak force of attraction. Thus, real gas will behave like an ideal gas.