Home / iGCSE Chemistry (0620) Theory (Core):2.6 Giant covalent structures: Exam Style Questions Paper 3

iGCSE Chemistry (0620) Theory (Core):2.6 Giant covalent structures: Exam Style Questions Paper 3- New Syllabus

iGCSE Chemistry Theory (Core) Paper 3 - All Chapters

Question

Fig.1.1 shows part of the Periodic Table.
Answer the following questions using only the symbols of the elements in Fig. 1.1.
Each symbol may be used once, more than once or not at all.
Give the symbol of the element that:
(a) is used as a lubricant
(b) forms an ion which is present in every dilute acid
(c) is a metal which does not react with steam 
(d) is in Period 3 and forms an ion with a charge of 1– when it reacts.

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

• Topic 2.2 — Atomic structure and the Periodic Table
• Topic 2.6 — Giant covalent structures (Graphite as lubricant)
• Topic 8.1 — Arrangement of elements

▶️ Answer/Explanation

(a) For the correct answer:
C

Explanation: Carbon in the form of graphite is used as a lubricant. Graphite has a layered giant covalent structure where weak forces between layers allow them to slide over each other easily, making it an effective dry lubricant.

(b) For the correct answer:
H

Explanation: Hydrogen forms the \(\text{H}^+\) ion, which is present in every dilute acid. According to the syllabus, aqueous solutions of acids contain \(\text{H}^+\) ions, which are responsible for their characteristic acidic properties.

(c) For the correct answer:
Ag

Explanation: Silver (Ag) is a metal placed below hydrogen in the reactivity series. Metals below hydrogen cannot displace hydrogen from water or steam, so silver does not react with steam.

(d) For the correct answer:
Cl

Explanation: Chlorine is located in Period 3, Group VII of the Periodic Table. It has 7 electrons in its outer shell and gains 1 electron when it reacts, forming the chloride ion \(\text{Cl}^-\), which carries a 1– charge.

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