1.1. The boiling points of the Group 6 hydrides are shown in the graph below:

i) Explain why the boiling points of the hydrides rise from H₂S to H₂Te

[1]

ii) Explain why the boiling point of H₂O does not follow this trend

[2]

1.2. Predict which of the following hydride pairs has the higher boiling point: 

i) CH₄ vs SiH₄

[1]

ii) NH₃ vs PH₃

[1]

iii) HF vs HCl

[1]

1.3. Explain how the physical properties of ammonia, NH₃, allow it to easily be separated in the Haber process from hydrogen and nitrogen gas, which can then be recycled.

1.4. The intermolecular forces between water molecules, H₂O, are stronger than those between ammonia molecules, NH₃.

Explain this difference.