This question is about Group IV elements and their compounds.
(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] [Total: 13]
▶️ Answer/Explanation
(a) Ans: A: Freezing (liquid to solid)
B: Boiling (liquid to gas)
(b) Ans: Separation: In liquid lead, particles are close together with some touching. In lead gas, particles are far apart.
Motion: In liquid lead, particles slide over each other with restricted movement. In lead gas, particles move freely and randomly.
(c) Ans: Lead(II) oxide loses oxygen (reduction) while carbon gains oxygen (oxidation).
(d)(i) Ans: Leaded petrol or lead-based paints are common sources of lead in air.
(d)(ii) Ans: Lead is toxic and can damage the nervous system and brain.
(e)(i) Ans: Giant (diamond has a giant covalent structure).
(e)(ii) Ans: Covalent bonding (each carbon atom forms four covalent bonds).
(e)(iii) Ans: Cutting tools/drill bits (due to diamond’s hardness).
(e)(iv) Ans: 2,4 (carbon has 2 electrons in the first shell and 4 in the outer shell).
Aqueous ammonia is an alkali.
(a) Complete the dot-and-cross diagram to show the electron arrangement in a molecule of ammonia.
(b) Complete the word equation for the reaction of aqueous ammonia with dilute hydrochloric acid.
(c) Describe the colour change when excess aqueous ammonia is added to an acidified solution of methyl orange.
(d) Aqueous ammonia reacts with aqueous copper(II) ions to produce compound B.
The formula of compound B is \(CuN_4H_{16}O_2\).
Complete the table to calculate the relative molecular mass of compound B.
relative molecular mass = …………………………
(e) Ammonia is used in the production of fertilisers.
State why farmers put fertilisers on the soil where crops are to be grown.
▶️ Answer/Explanation
(a) Ans:
• The dot-and-cross diagram should show:
– 3 bonding pairs (1 electron from each H and 1 from N) between N and each H.
– 1 lone pair (2 electrons) on the nitrogen atom.
(b) Ans: ammonia + hydrochloric acid → ammonium chloride
The neutralization reaction forms ammonium chloride (NH₄Cl), a salt.
(c) Ans: from red/pink to yellow
Methyl orange is red in acidic solutions and yellow in alkaline solutions. Excess ammonia makes the solution alkaline.
(d) Ans: 168
Calculated as:
Cu (64) + 4×N (4×14 = 56) + 16×H (16×1 = 16) + 2×O (2×16 = 32) = 64 + 56 + 16 + 32 = 168.
(e) Ans: To provide essential nutrients for plant growth
Fertilisers supply nitrogen, phosphorus, and potassium, which are vital for healthy plant growth and increased crop yield.