Home / iGCSE Chemistry 0620 Extended – 10.2 Fertilisers- Exam Style Questions Paper 4

iGCSE Chemistry 0620 Extended - 10.2 Fertilisers- Exam Style Questions Paper 4- New Syllabus

iGCSE Chemistry Theory (Extended) Paper 4 - All Chapters

Question

(a) The symbols of the elements in Period 3 of the Periodic Table are shown.
Na   Mg   Al   Si   P   S   Cl   Ar
Use the symbols of the elements in Period 3 to answer the questions that follow. Each symbol may be used once, more than once, or not at all. Give the symbol of the element that:
(i) is present in purified bauxite
(ii) contains atoms with a full outer shell of electrons
(iii) is used to kill microbes in water treatment
(iv) forms an amphoteric oxide
(v) forms an oxide which causes acid rain
(vi) has an oxidation number of -1 when it forms a compound with hydrogen.
(b) The relative atomic masses of elements can be calculated from the relative masses of isotopes and their percentage abundances.
(i) Identify the isotope to which all relative masses are compared.
(ii) Table 2.1 shows the relative masses and the percentage abundances of the two isotopes in a sample of magnesium.
Calculate the relative atomic mass of magnesium to one decimal place.
(c) An ion contains 10 electrons, 13 protons and 14 neutrons.
(i) State the nucleon number of the ion.
(ii) Identify the element that forms this ion.

Most-appropriate topic codes (Cambridge IGCSE Chemistry 0620):

• Topic 8.2 — Periodicity / Topic 9.5 — Extraction of Metals (Part (a)(i), (a)(ii) & (a)(iv))
• Topic 10.2 — Water supply and water treatment (Part (a)(iii))
• Topic 10.3 — Air quality and climate (Part (a)(v))
• Topic 6.4 — Redox reactions (Part (a)(vi))
• Topic 2.2 — Isotopes and relative atomic mass (Part (b)(i) & (b)(ii))
• Topic 2.1 — Atomic structure (Part (c)(i) & (c)(ii))

▶️ Answer/Explanation

(a)(i) Al
Bauxite serves as the primary metal mineral source for extracting pure aluminium. It goes through intermediate chemical upgrades to clean out solid iron impurities prior to down-stream electrolysis.

(a)(ii) Ar
Argon is an unreactive noble gas situated at the far right edge of Period 3. Because its valence ring contains a completed octet layout, it remains extremely inert and chemically detached.

(a)(iii) Cl
Chlorine acts as a highly effective antimicrobial treatment chemical. Municipal utilities disperse tiny trace doses throughout raw water to sterilize bacterial cells and secure clean tap delivery.

(a)(iv) Al
Aluminium oxide ($\text{Al}_2\text{O}_3$) behaves as an amphoteric chemical species. This lets it neutralize acidic compounds as well as highly alkaline bases during chemical processing.

(a)(v) S
Sulfur burns to generate sulfur dioxide gas. Once launched into cloud moisture layers, this compound oxidizes into acid rain mixtures that can impact environmental ecosystems.

(a)(vi) Cl
Chlorine holds a strong electron affinity compared to hydrogen. Within hydrogen chloride gas, the chlorine atom pulls shared electron density close to itself, claiming a $-1$ oxidation state.

(b)(i) Carbon-12 (${}^{12}\text{C}$)
The common reference baseline globally for all relative atomic weights is standard Carbon-12. This particular atomic isotope acts as the perfect benchmark for comparing mass quantities safely.

(b)(ii) 24.3
We calculate the weighted average based on isotopic masses and how often they appear in nature: $$\text{A}_r = \frac{(24 \times 85) + (26 \times 15)}{100} = \frac{2040 + 390}{100} = 24.3$$

(c)(i) 27
The nucleon count is found by adding together the total number of protons and neutrons located inside the atomic nucleus. Adding them together gives $13 \text{ protons} + 14 \text{ neutrons} = 27$.

(c)(ii) Aluminium / Al
The definitive identification for any element is governed by its proton count. Finding exactly 13 protons in the nucleus matches exclusively with the atomic properties of aluminium.

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