1 Key concepts in chemistry

Practice questions on Key concepts in chemistry

• Iron rusts when it reacts with oxygen and water. A student leaves an iron nail in moist ai… (4 marks, Explain)
• Magnesium reacts with oxygen to form magnesium oxide. Explain why the mass of magnesium ox… (4 marks, Explain)
• Explain why magnesium has a high melting point and conducts electricity. (4 marks, Explain)
• Explain why silicon dioxide has a high melting point and does not conduct electricity. (4 marks, Explain)
• Explain why iodine has a low melting point and does not conduct electricity. (4 marks, Explain)
• Explain why water (H₂O) is a liquid at room temperature but methane (CH₄) is a gas at room… (4 marks, Explain)
• Explain why iodine (I₂) does not conduct electricity in any state and has a low melting po… (4 marks, Explain)
• Explain why silicon dioxide has a much higher melting point than carbon dioxide, even thou… (4 marks, Explain)
• Magnesium oxide is an ionic compound. Explain how magnesium oxide is formed when magnesium… (4 marks, Explain)
• Explain why sodium chloride has a high melting point. (4 marks, Explain)
• Explain what is meant by the term 'isotopes' and describe how two isotopes of the same ele… (4 marks, Explain)
• Explain how the results of the alpha particle scattering experiment led scientists to conc… (4 marks, Explain)
• Describe the structure of an atom in terms of the particles it contains, including where t… (4 marks, Describe)
• Describe how the atomic model has changed from the 'plum pudding' model to the nuclear mod… (4 marks, Describe)
• A student has prepared a mixture containing iron filings and sulfur powder. The student th… (4 marks, Explain)
• A student has prepared a sample of copper sulfate crystals from a reaction mixture that al… (4 marks, Explain)
• A student wants to separate a mixture of two liquids that are miscible with each other and… (4 marks, Describe)
• A student has a mixture of sand and salt dissolved in water. Describe how the student coul… (4 marks, Describe)
• Explain why a substance in the liquid state can flow and take the shape of its container, … (4 marks, Explain)
• Explain why a substance in the gaseous state has a much lower density than the same substa… (4 marks, Explain)