Question 1: Define a simple molecule in terms of covalent bonding.

Answer: A molecule made up of a small number of non-metal atoms held together by covalent bonds.

Question 2: Explain why noble gases are generally monatomic and do not form simple molecules under normal conditions.

Answer: Noble gases have full outer electron shells, making them chemically stable and unlikely to form covalent bonds with other atoms.

Question 3: Describe the main difference between ionic and covalent bonding in simple molecules.

Answer: Covalent bonding involves sharing electron pairs between non-metal atoms, whereas ionic bonding involves transfer of electrons between metal and non-metal atoms.

Question 1: Calculate the molar mass of a molecule of water (H₂O). (Atomic masses: H = 1.0 u, O = 16.0 u)

Answer: 18.0 g/mol

Question 2: Determine the number of molecules in 36 grams of carbon dioxide (CO₂). (Atomic masses: C = 12.0 u, O = 16.0 u, Avogadro's number = 6.022×10²³ mol⁻¹)

Answer: Approximately 1.51×10²⁴ molecules

Question 1: Describe a simple experiment to demonstrate the formation of a covalent bond between two non-metal gases, including safety precautions.

Answer: A safe demonstration involves mixing hydrogen and oxygen gases in a controlled environment and igniting with a spark to form water, ensuring proper ventilation, no open flames nearby, and protective equipment.

Question 2: Identify three variables that could affect the formation of simple molecules in a laboratory setting and how they might influence the outcome.

Answer: Temperature, pressure, and concentration; higher temperature can increase reaction rate, higher pressure can favour molecule formation, and concentration affects collision frequency.

Question 1: A sample of methane (CH₄) has a molar mass of approximately 16.0 g/mol. If 32 grams of methane are burned completely, how many moles of carbon dioxide are produced? (Assume complete combustion and that all carbon forms CO₂).

Answer: 2 moles of CO₂

Question 1: Explain how knowledge of covalent bonding in simple molecules is important in the development of pharmaceuticals.

Answer: Understanding covalent bonds helps chemists design molecules with specific properties, ensuring drugs are effective, stable, and safely interact with biological targets.

Question 2: Identify a daily life product that relies on simple covalent molecules and describe how their molecular properties are utilised.

Answer: Water (H₂O) is used in cleaning and cooking; its polarity and hydrogen bonding due to covalent molecules give it unique solvent properties.