Question

1. which water is likely to be hard?

a the clear water in the cup.
b the muddy water in the bucket.
c the water vapour within the bucket.
d the water droplets on the plastic sheet.

1. a metal rod has the following properties;

(i) it is attracted by magnets
(ii) it conducts electricity
(iii) it bends without breaking

which properties of the rod are common to all metals?
a (i) and (ii)
b (i) and (iii)
c (ii) and (iii)
d (i), (ii) and (iii)

1. the diagram below shows an experimental set-up used to demonstrate how heating air affects its volume.

the electric stove is switched on.

which row in the table below describes and explains what is likely to happen in the experiment?

\

$$\begin{tabular}{|c|l|l|} \\hline & description & explanation \\\\ \\hline a & the water droplet moves downwards & air in the flask contracts \\\\ \\hline b & the water droplet moves downwards & air in the flask expands \\\\ \\hline c & the water droplet moves upwards & air in the flask contracts \\\\ \\hline d & the water droplet moves upwards & air in the flask expands \\\\ \\hline \\end{tabular}$$

Explanation:

🆕 New Concept Discovered: Thermal Expansion of Gases
Heating a gas makes it expand and take up more space.

Step 1: Analyze the effect of heating on air

When the electric stove is switched on, it heats the flask containing air. Heating a gas increases the kinetic energy of its particles, causing them to move faster and spread further apart. This process is called thermal expansion. Therefore, the air inside the flask expands.

Step 2: Determine the movement of the water droplet

As the air inside the flask expands, it requires more volume (space). Since the flask is sealed at the bottom, the expanding air pushes upward through the glass tube. This upward pressure pushes the water droplet in the tube upwards.

Step 3: Match with the table options

Let's evaluate the given options based on our findings:

• Description: The water droplet moves upwards.
• Explanation: Air in the flask expands.

This matches option D.

Answer:

D