(a) The changes of state of lead are shown.
Name the changes of state represented by A and B.[2]
A
B
(b) Use the kinetic particle model to describe the differences between liquid lead and lead gas in terms of:[4]
- the separation of the particles
- the motion of the particles.
(c) Lead is extracted from lead(II) oxide by heating with carbon.
PbO + C → Pb + CO
Describe how this equation shows that lead(II) oxide is reduced.[1]
(d) Lead is a pollutant of the air.
(i) State one source of lead in the air.[1]
(ii) State one adverse effect of lead on health.[1]
(e) Diamond is a form of carbon.
The structure of diamond is shown.
(i) Choose the word which best describes the structure of diamond.
Draw a circle around your chosen answer.[1]
giant ionic metallic simple
(ii) Name the type of bonding in diamond.[1]
(iii) Give one use of diamond.[1]
(iv) Deduce the electronic structure of carbon.
Use the Periodic Table to help you.[1]
▶️ Answer/Explanation
(a) Ans: A: freezing, B: boiling
A represents the transition from liquid to solid (freezing), and B represents the transition from liquid to gas (boiling).
(b) Ans:
Separation: In liquid lead, particles are close together with some touching, while in lead gas, particles are far apart.
Motion: In liquid lead, particles slide over each other with restricted movement, whereas in lead gas, particles move freely and rapidly.
(c) Ans: Lead(II) oxide loses oxygen.
Reduction involves the loss of oxygen. Here, PbO loses oxygen to form Pb.
(d)(i) Ans: (leaded) petrol / paints
Lead enters the air primarily from vehicle emissions or old lead-based paints.
(d)(ii) Ans: poisonous / toxic / harms nerves / harms brain
Lead exposure can cause severe neurological and developmental damage.
(e)(i) Ans: giant
Diamond has a giant covalent structure with a continuous network of carbon atoms.
(e)(ii) Ans: covalent
Diamond’s carbon atoms are bonded by strong covalent bonds.
(e)(iii) Ans: cutting tools / jewelry
Diamond’s hardness makes it ideal for industrial cutting or decorative uses.
(e)(iv) Ans: 2,4
Carbon (atomic number 6) has 2 electrons in the first shell and 4 in the second.
(a) The structures of four substances C, D, E, and F are shown.
(i) Which one of these substances, C, D, E, or F, is a gas at room temperature?
(ii) What type of bonding is present in substance E?
(iii) Which one of these substances, C, D, E, or F, is soluble in water?
(iv) Which one of these substances, C, D, E, or F, conducts electricity when solid?
(b) The halogens have molecules containing two atoms. What is the name for molecules containing only two atoms?
(c) The reaction of iodine with hydrogen is shown.
\(I_2 + H_2 \leftrightarrow 2HI\)
What is the meaning of the symbol \(\leftrightarrow\)?
(d) Iodine is formed when chlorine reacts with aqueous potassium iodide.
(i) Complete the chemical equation for this reaction.
\(………. + 2KI → I_2 + …….KCl\)
(ii) When aqueous iodine is mixed with aqueous potassium chloride, there is no reaction. Suggest, in terms of chemical reactivity, why there is no reaction.
▶️ Answer/Explanation
(a)
(i) F (Simple molecular substances with weak intermolecular forces are gases at room temperature.)
(ii) Ionic bonding (E has a lattice structure typical of ionic compounds.)
(iii) E (Ionic compounds like E dissolve in polar solvents like water.)
(iv) D (Metals conduct electricity due to delocalized electrons.)
(b) Diatomic (Molecules with two atoms are called diatomic.)
(c) Reversible reaction (The symbol \(\leftrightarrow\) indicates the reaction can proceed in both directions.)
(d)
(i) \(Cl_2 + 2KI → I_2 + 2KCl\) (Chlorine displaces iodine from potassium iodide.)
(ii) Chlorine is more reactive than iodine, so the reverse reaction does not occur.