1 What is the type of particles in neon? flag bookmark A Ion B Atom C Molecule T4 Chapter 2.1 Basic Concepts of Matter Neon is a noble gas. Its atoms already have a stable octet, so they do not combine with each other or with other atoms. Neon exists as single atoms (a monatomic gas).
2 Which of the following isotopes is used to detect the leakage of underground pipes? flag bookmark A Carbon-14 B Sodium-24 C Cobalt-60 D Iodine-131 T4 Chapter 2.4 Isotopes and Its Uses Sodium-24 is a radioactive isotope with a short half-life. It is added to the water in the pipe, and a Geiger-Müller counter finds where the radiation is unusually high, which shows the leak. Carbon-14 is used for dating fossils, cobalt-60 for cancer treatment and iodine-131 for thyroid problems.
3 Which of the following is the correct formula of an ion? flag bookmark A $\text{Al}^+$ B $\text{Al}^{3+}$ C $\text{Ag}^{2+}$ D $\text{Ag}^{3+}$ T4 Chapter 3.3 Chemical Formula Aluminium (2.8.3) loses its 3 valence electrons to form $\text{Al}^{3+}$. Silver forms the $\text{Ag}^+$ ion, so $\text{Ag}^{2+}$ and $\text{Ag}^{3+}$ are wrong, and $\text{Al}^+$ does not form.
4 What is the meaning of the Avogadro constant? flag bookmark A The mass of one mole of a substance B The pressure of one mole of a substance C The number of particles in one mole of a substance D The volume occupied by one mole of gas T4 Chapter 3.2 Mole Concept The Avogadro constant ($6.02 \times 10^{23}\ \text{mol}^{-1}$) is the number of particles (atoms, ions or molecules) in one mole of a substance. The mass of one mole is the molar mass, and the volume of one mole of gas is the molar volume.
5 Which of the following elements form acidic oxides when they react with oxygen? I. Sulphur II. Sodium III. Phosphorus IV. Magnesium flag bookmark A I and III B I and IV C II and III D II and IV T4 Chapter 4.6 Elements in Period 3 Non-metals form acidic oxides: sulphur forms $\text{SO}_2$ and phosphorus forms $\text{P}_4\text{O}_{10}$, which dissolve in water to give acids. Sodium and magnesium are metals that form basic oxides.
6 Diagram 1 shows the formation of a type of bond in an ion. What is the type of the bond? flag bookmark A Hydrogen bond B Metallic bond C Dative bond D Ionic bond T4 Chapter 5.5 Dative Bond The oxygen atom in water donates its lone pair to the $\text{H}^+$ ion, which has no electrons. The shared pair comes from one atom only, so a dative (coordinate) bond is formed, giving the hydroxonium ion $\text{H}_3\text{O}^+$.
7 Which of the following salts is prepared through a double decomposition reaction? flag bookmark A Ammonium carbonate B Magnesium chloride C Calcium nitrate D Barium sulphate T4 Chapter 6.9 Preparation of Salts Double decomposition (precipitation) is used to prepare insoluble salts. Barium sulphate is insoluble, so it is made by mixing a solution containing $\text{Ba}^{2+}$ ions with one containing $\text{SO}_4^{2-}$ ions. Ammonium carbonate, magnesium chloride and calcium nitrate are soluble salts.
8 What is the catalyst used to increase the rate of reaction between zinc and hydrochloric acid? flag bookmark A Nickel B Iron C Copper(II) sulphate D Manganese(IV) oxide T4 Chapter 7.2 Factors Affecting Rate of Reactions A little copper(II) sulphate solution speeds up the reaction between zinc and acid: zinc displaces some copper, and the copper on the zinc surface makes hydrogen form faster. Nickel is used in hydrogenation, iron in the Haber process and manganese(IV) oxide in the decomposition of hydrogen peroxide.
9 Photochromic glass is a composite material used in the manufacture of car windows and building windows. Which of the following are the strengthening substances in photochromic glass? I. Copper(I) chloride II. Iron(II) chloride III. Silver chloride IV. Barium chloride flag bookmark A I and III B I and IV C II and III D II and IV T4 Chapter 8.4 Composite Materials and Its Importance Photochromic glass is glass (matrix) combined with silver chloride and copper(I) chloride (strengthening substances). Silver chloride darkens in sunlight, and copper(I) chloride helps the glass become clear again in dim light.
10 Diagram 2 shows the uses of two different materials, P and Q. What is the main element in materials P and Q? flag bookmark A Iron B Carbon C Tin D Copper T4 Chapter 8.1 Alloy and Its Importance P (surgical instruments) is made of stainless steel and Q (railway tracks) is made of steel. Both are alloys of iron, so the main element is iron.