Completed worksheet demonstrating the difference between physical properties, such as color and density, and chemical properties like reactivity.

Problem Overview:

The task is to classify each statement as either a physical property or a chemical property and identify the specific type of property. Physical properties are characteristics that can be observed or measured without changing the identity of the substance, while chemical properties describe how a substance reacts with other substances.

Solution:

Below is the detailed classification for each statement:

---

#### 1. The sulphur is yellow.
- Physical/Chemical: Physical
- Type: Colour
- Explanation: The color of sulfur (yellow) is an observable characteristic that does not involve a chemical reaction or change in its identity.

#### 2. Iron reacts with sulphur to give heat and a flame.
- Physical/Chemical: Chemical
- Type: Combustibility; Reaction
- Explanation: This involves a chemical reaction between iron and sulfur, producing heat and a flame, which indicates a chemical change.

#### 3. Baking soda with acid produces bubbles of gas.
- Physical/Chemical: Chemical
- Type: Reaction with acid
- Explanation: The production of gas when baking soda reacts with acid is a chemical reaction, indicating a chemical property.

#### 4. Metal can be rolled into flat sheets.
- Physical/Chemical: Physical
- Type: Malleability
- Explanation: The ability of a metal to be rolled into flat sheets is a physical property related to its malleability, which describes its deformation under pressure without breaking.

#### 5. Oxygen is colourless, odourless and tasteless.
- Physical/Chemical: Physical
- Type: Colour, odour, taste
- Explanation: These are observable characteristics of oxygen without any chemical reaction occurring.

#### 6. Nitrogen dioxide gas has a choking smell.
- Physical/Chemical: Physical
- Type: Odour
- Explanation: The smell of nitrogen dioxide is a physical property because it describes the odor without altering the substance's identity.

#### 7. Helium is less dense than air, so a helium balloon floats.
- Physical/Chemical: Physical
- Type: Density
- Explanation: The density of helium compared to air is a physical property that explains why helium balloons float.

#### 8. Wax candle burns in oxygen.
- Physical/Chemical: Chemical
- Type: Combustibility
- Explanation: The burning of a wax candle in oxygen is a chemical reaction involving combustion.

#### 9. An apple rots due to fungi.
- Physical/Chemical: Chemical
- Type: Reaction
- Explanation: The rotting of an apple due to fungi involves a chemical reaction, indicating a chemical property.

#### 10. Mercury metal is a liquid.
- Physical/Chemical: Physical
- Type: State
- Explanation: The state of mercury (liquid) is a physical property that describes its phase at room temperature.

#### 11. Iodine gas is purple.
- Physical/Chemical: Physical
- Type: Colour
- Explanation: The color of iodine gas (purple) is a physical property that can be observed without a chemical change.

#### 12. Hydrofluoric acid is poisonous.
- Physical/Chemical: Chemical
- Type: Reaction
- Explanation: The toxicity of hydrofluoric acid is a chemical property because it involves a chemical reaction with biological systems.

#### 13. Gold is a shiny metal.
- Physical/Chemical: Physical
- Type: Lustre
- Explanation: The shininess of gold is a physical property related to its lustre, which describes how light reflects off its surface.

#### 14. Cesium is the only other gold-coloured metal.
- Physical/Chemical: Physical
- Type: Colour
- Explanation: The color of cesium (gold-colored) is a physical property that can be observed without a chemical change.

#### 15. Potassium burns with a purple flame to make a white powder.
- Physical/Chemical: Chemical
- Type: Combustibility
- Explanation: The burning of potassium with a purple flame and the formation of a white powder indicate a chemical reaction, making this a chemical property.

#### 16. Copper nitrate is a blue crystal.
- Physical/Chemical: Physical
- Type: Colour, crystal form
- Explanation: The blue color and crystalline structure of copper nitrate are physical properties that can be observed without a chemical change.

#### 17. Two colourless solutions mix to give a yellow solid precipitate.
- Physical/Chemical: Chemical
- Type: Reaction
- Explanation: The formation of a yellow solid precipitate when two solutions mix indicates a chemical reaction.

#### 18. Copper can be stretched into a thin wire.
- Physical/Chemical: Physical
- Type: Ductility
- Explanation: The ability of copper to be stretched into a thin wire is a physical property related to its ductility.

#### 19. Copper metal reacts with nitric acid to make a brown gas.
- Physical/Chemical: Chemical
- Type: Reaction with acid
- Explanation: The reaction of copper with nitric acid to produce a brown gas is a chemical reaction, indicating a chemical property.

#### 20. Salt, sodium chloride, is a white crystal that melts at 801 °C.
- Physical/Chemical: Physical
- Type: Colour, crystal form, melting point
- Explanation: The white color, crystalline structure, and melting point of sodium chloride are all physical properties that can be observed or measured without a chemical change.

---

Final Answer:

\[
\boxed{
\begin{array}{|c|c|c|}
\hline
\text{Description} & \text{Physical/Chemical} & \text{Type} \\
\hline
1. \text{The sulphur is yellow.} & \text{Physical} & \text{Colour} \\
2. \text{Iron reacts with sulphur to give heat and a flame.} & \text{Chemical} & \text{Combustibility; Reaction} \\
3. \text{Baking soda with acid produces bubbles of gas.} & \text{Chemical} & \text{Reaction with acid} \\
4. \text{Metal can be rolled into flat sheets.} & \text{Physical} & \text{Malleability} \\
5. \text{Oxygen is colourless, odourless and tasteless.} & \text{Physical} & \text{Colour, odour, taste} \\
6. \text{Nitrogen dioxide gas has a choking smell.} & \text{Physical} & \text{Odour} \\
7. \text{Helium is less dense than air, so a helium balloon floats.} & \text{Physical} & \text{Density} \\
8. \text{Wax candle burns in oxygen.} & \text{Chemical} & \text{Combustibility} \\
9. \text{An apple rots due to fungi.} & \text{Chemical} & \text{Reaction} \\
10. \text{Mercury metal is a liquid.} & \text{Physical} & \text{State} \\
11. \text{Iodine gas is purple.} & \text{Physical} & \text{Colour} \\
12. \text{Hydrofluoric acid is poisonous.} & \text{Chemical} & \text{Reaction} \\
13. \text{Gold is a shiny metal.} & \text{Physical} & \text{Lustre} \\
14. \text{Cesium is the only other gold-coloured metal.} & \text{Physical} & \text{Colour} \\
15. \text{Potassium burns with a purple flame to make a white powder.} & \text{Chemical} & \text{Combustibility} \\
16. \text{Copper nitrate is a blue crystal.} & \text{Physical} & \text{Colour, crystal form} \\
17. \text{Two colourless solutions mix to give a yellow solid precipitate.} & \text{Chemical} & \text{Reaction} \\
18. \text{Copper can be stretched into a thin wire.} & \text{Physical} & \text{Ductility} \\
19. \text{Copper metal reacts with nitric acid to make a brown gas.} & \text{Chemical} & \text{Reaction with acid} \\
20. \text{Salt, sodium chloride, is a white crystal that melts at 801 °C.} & \text{Physical} & \text{Colour, crystal form, melting point} \\
\hline
\end{array}
}
\]