Home / AS & A Level Chemistry 3.6 Intermolecular forces, electronegativity and bond properties Exam Style Practice Questions Paper 1
The boiling point of water, \(\mathrm{H_2O}\), is higher than that of hydrogen sulfide, \(\mathrm{H_2S}\).
Which statement explains this difference in boiling points?
Correct Answer: \( \boxed{\mathrm{D}} \)
Water molecules form extensive intermolecular hydrogen bonds because hydrogen is bonded to the highly electronegative oxygen atom.
Hydrogen sulfide does not form significant hydrogen bonding, so only weaker intermolecular forces act between its molecules.
Stronger intermolecular forces require more energy to overcome, giving water a much higher boiling point.
Therefore, the correct answer is (D).
Which oxide has a simple structure rather than a giant structure?
Correct Answer: \( \boxed{\mathrm{D}} \)
\(\mathrm{MgO}\) and \(\mathrm{Al_2O_3}\) are giant ionic lattices.
\(\mathrm{SiO_2}\) has a giant covalent network structure.
\(\mathrm{P_4O_{10}}\) consists of discrete covalent molecules and therefore has a simple molecular structure.
Therefore, the correct answer is (D).
Consider the following statements.
1. Silicon dioxide has a higher melting point than sulfur dioxide.
2. Ammonia has a higher boiling point than phosphine, \( \mathrm{PH_3} \).
Which statements are correct?
Correct Answer: \( \boxed{\mathrm{A}} \)
Statement 1: True. Silicon dioxide has a giant covalent structure with many strong \( \mathrm{Si-O} \) bonds, giving it a very high melting point. Sulfur dioxide is a simple molecular substance with weak intermolecular forces, so its melting point is much lower.
Statement 2: True. Ammonia forms intermolecular hydrogen bonds, whereas phosphine does not. Hydrogen bonding makes the boiling point of ammonia higher than that of \( \mathrm{PH_3} \).
Therefore, both statements are correct. Hence, the correct answer is (A).