Properties of Matter：練習問題

Which of the following properties of air is best demonstrated when a student blows air into a balloon and it expands?

A student has a solid piece of plasticine. When rolled into a tight ball, it sinks in water. However, when molded into a hollow bowl shape, it floats. Which of the following best explains this observation?

A burning candle is placed on a table and covered with a large glass jar. After a short time, the flame flickers and goes out. Based on the requirements for combustion, why did the flame extinguish?

Which of the following substances does not have a fixed shape but does have a fixed volume at room temperature?

When cooking oil is poured into a glass of water, it stays in a layer on top of the water. This observation proves that oil:

Explain why copper is used for the internal part of electrical wires while plastic is used for the outer coating, based on their physical properties.

A student drops a stone and a cork into a basin of water. Describe the buoyancy observed for both objects and explain what this indicates about their properties compared to water.

When a wax candle is lit, the wax near the wick melts into a liquid, while the wick itself burns away. Identify which of these is a physical change and which is a chemical change, and provide one reason for your choice.

A teacher places a copper coin and a plastic ruler on a table for an experiment.
(a) If both objects are connected one at a time into a simple electrical circuit with a battery and a bulb, which object will cause the bulb to light up? Name the physical property that explains this.
(b) Both objects are then placed in a bowl of hot water at \( 60 \) degrees Celsius for \( 5 \) minutes. Which object will feel hotter when touched? Name the physical property involved.

A student conducts an experiment with a clear glass, a basin of water, and a dry tissue paper.
(a) The student stuffs the dry tissue into the bottom of the glass and pushes the glass vertically downwards, mouth-first, into the water until it is completely submerged. Predict whether the tissue will get wet and explain your answer using the properties of air.
(b) While the glass is submerged, the student tilts it slightly to one side. They observe bubbles rising to the surface. What does this observation prove about the space inside the glass?
(c) In a separate experiment, the student places a solid iron ball and a wooden block of the same volume into the water. The iron ball sinks while the wooden block floats. Explain this phenomenon by comparing the weight of the objects and the buoyancy (upward force) acting on them.