Estimate the density of the following gases at the conditions given: 

1. Hydrogen at 20 bara and 230°C;   

2. Ammonia at 1 bara and 50°C and at 100 bara and 300°C; 

3. Nitrobenzene at 20 bara and 230°C; 

4. Water at 100 bara and 500°C. Check your answer using steam tables; 

5. Benzene at 2 barg and 250°C; 

6. Synthesis gas (N₂ + 3H₂) at 5 barg and 25°C.