Covalent bonds involve

41. Sulphur dioxide is mainly produced by burning:
Sulphur dioxide ($\text{SO}_2$) is formed when sulphur (S) burns in oxygen.
The reaction is $\text{S} + \text{O}_2 \rightarrow \text{SO}_2$.

• C. Sulphur

42. The industrial process used to manufacture sulphuric acid is the:
The Contact process is the industrial method for producing sulphuric acid ($\text{H}_2\text{SO}_4$).

• A. Contact process

43. Which allotrope of sulphur is stable at room temperature?
Rhombic sulphur (alpha-sulphur) is the most stable allotrope of sulphur at room temperature (below 95.6 °C).

• B. Rhombic sulphur

44. Sulphur trioxide reacts with water to produce:
Sulphur trioxide ($\text{SO}_3$) is the anhydride of sulphuric acid. When it reacts with water, it forms sulphuric acid.
The reaction is $\text{SO}_3 + \text{H}_2\text{O} \rightarrow \text{H}_2\text{SO}_4$.

• B. $\text{H}_2\text{SO}_4$

45. A use of sulphur dioxide in food industries is as a:
Sulphur dioxide is commonly used as a food preservative due to its antimicrobial and antioxidant properties, for example, in dried fruits and wine.

• B. Preservative

46. Ionic bonding occurs between:
Ionic bonding involves the transfer of electrons, typically from a metal atom to a non-metal atom, forming ions that are attracted to each other.

• B. Metals and non-metals

47. Covalent bonds involve:
Covalent bonding involves the sharing of electron pairs between atoms, typically between two non-metal atoms.

• B. Sharing of electrons

48. Metallic bonding is characterised by:
Metallic bonding is characterized by a "sea" of delocalised valence electrons that are shared among a lattice of positive metal ions.

• C. Sea of delocalised electrons

49. A molecule with a linear shape is:
Using VSEPR theory:

• A. $\text{CO}_2$: The central carbon atom has two double bonds and no lone pairs, resulting in a linear shape.
• B. $\text{H}_2\text{O}$: The central oxygen atom has two bonding pairs and two lone pairs, resulting in a bent shape.
• C. $\text{NH}_3$: The central nitrogen atom has three bonding pairs and one lone pair, resulting in a trigonal pyramidal shape.
• D. $\text{CH}_4$: The central carbon atom has four bonding pairs and no lone pairs, resulting in a tetrahedral shape.
• A. $\text{CO}_2$

50. Hydrogen bonding occurs in:
Hydrogen bonding occurs when a hydrogen atom is directly bonded to a highly electronegative atom (nitrogen, oxygen, or fluorine) and is attracted to another electronegative atom in a different molecule.

• A. $\text{O}_2$: No hydrogen atoms.
• B. $\text{CH}_4$: Hydrogen is bonded to carbon, which is not electronegative enough to form hydrogen bonds.
• C. $\text{NH}_3$: Hydrogen is bonded to nitrogen, which is highly electronegative, allowing for hydrogen bonding between $\text{NH}_3$ molecules.
• D. $\text{NaCl}$: This is an ionic compound, not a molecule that forms hydrogen bonds.
• C. $\text{NH}_3$