1 Which of the following substances exists as molecules at room temperature? flag bookmark A Chlorine B Potassium C Carbon D Krypton T4 Chapter 4.5 Elements in Group 17 Chlorine exists as diatomic Cl₂ molecules at room temperature, unlike potassium, carbon, or krypton, which are not molecular.
2 Who is the scientist that discovered the electron? flag bookmark A Niels Bohr B J. J. Thomson C James Chadwick D Ernest Rutherford T4 Chapter 2.2 The Development of the Atomic Model J. J. Thomson discovered the electron through cathode ray experiments. Bohr modelled atomic orbits, Rutherford found the nucleus, and Chadwick discovered the neutron.
3 Which of the following statements explains why carbon-12 was chosen as the standard atom to determine the relative atomic mass and relative molecular mass? flag bookmark A Carbon is easy to handle B Carbon is an inert element C Carbon has three isotopes D Carbon is a non-metal element T4 Chapter 3.1 Relative Atomic Mass and Relative Molecular Mass Carbon-12 was chosen as the standard because it is a solid, stable, and easy to handle, making it practical for weighing and comparing atomic masses.
4 Diagram 1 shows the apparatus set-up to determine the empirical formula of magnesium oxide. Which of the following steps is correct to ensure that the magnesium ribbon is burnt completely? flag bookmark A Rub the magnesium ribbon with sandpaper B Open the crucible lid at intervals during heating C Heat the magnesium ribbon strongly in the covered crucible D Repeat the heating, cooling and weighing process until a constant mass is obtained T4 Chapter 3.3 Chemical Formula Reheating, cooling and weighing until the mass stays constant shows no further change is occurring, confirming all the magnesium has reacted completely with oxygen.
5 Which of the following are the uses of helium gas? - I. Used in weather balloons - II. Used in the oxygen tanks of divers - III. Used in lasers for eye retina treatment - IV. Used in the flashlights of cameras flag bookmark A I and II B I and IV C II and III D III and IV T4 Chapter 4.3 Elements in Group 18 Helium is lighter than air, so it lifts weather balloons, and it is mixed with oxygen in divers’ tanks to prevent nitrogen narcosis. Retina lasers use argon, while camera flashlights use xenon.
6 Which of the following substances produces a yellow colour when universal indicator is added to it? flag bookmark A Milk B Blood C Tomato D Soap T4 Chapter 6.2 pH Value Tomato is acidic, so universal indicator turns yellow, indicating a pH around 4–5.
7 Diagram 2 shows the formation of the metallic bond in magnesium. What is Y? flag bookmark A Ion B Atom C Proton D Electron T4 Chapter 5.6 Metallic Bond Y points to a dot, which represents a delocalised electron. In a metallic bond, the Mg2+ ions are surrounded by a "sea" of these delocalised electrons.
8 Nickel powder is used as a catalyst for the hydrogenation of ethene. How does the catalyst increase the rate of the reaction? flag bookmark A Lowers the activation energy of the reaction B Increases the kinetic energy of the reactant particles C Increases the total number of reactant particles D Breaks the double bonds between carbon atoms in ethene molecules T4 Chapter 7.4 Collision Theory A catalyst provides an alternative reaction pathway with lower activation energy, so more ethene particles have sufficient energy to react, increasing the rate.
9 The National Monument of Malaysia is made of an alloy. Which of the following substances are the components of the alloy? flag bookmark A Iron and carbon B Iron and chromium C Copper and zinc D Copper and tin T4 Chapter 8.1 Alloy and Its Importance The National Monument is made of bronze, an alloy of copper and tin, so option D is correct.
10 Which of the following are the properties of ceramics? - I. Electrical insulator - II. Chemically inert - III. Hard but brittle - IV. Low heat resistance flag bookmark A I and II B I and IV C II and III D III and IV T4 Chapter 8.3 Composition of Ceramics and Its Uses Ceramics are electrical insulators (I), chemically inert (II) and hard but brittle (III); only IV is wrong because ceramics have high heat resistance. Options A (I and II) and C (II and III) both contain only correct properties, so both are accepted.