Physical and chemical changes：練習問題

Which of the following processes is a physical change?

Which statement correctly describes a chemical change compared to a physical change?

The graph shows the heating curve of a pure solid substance. During a period of 3 minutes, the temperature remains constant at \(55^\circ C\) as the solid melts.
Which statement correctly describes the particles during these 3 minutes?

Which of the following processes represents a physical change rather than a chemical change?

Which statement correctly describes the change that occurs when water is added to anhydrous copper(II) sulfate?

State the primary difference between a physical change and a chemical change in terms of the substances produced.

Classify the following two changes as physical or chemical:
(i) The boiling of water to form steam.
(ii) The heating of magnesium ribbon in air to form a white powder.

A student investigates two different processes involving magnesium.
Process 1: A piece of magnesium ribbon is added to a beaker of dilute hydrochloric acid. The beaker becomes warm and a gas is evolved.
Process 2: A piece of magnesium ribbon is heated strongly in a crucible until it melts and eventually forms a white powder after reacting with air.

(a) Identify which process represents a physical change and which represents a chemical change.
(b) Describe one piece of evidence from the descriptions above that supports your identification of Process 1 as a chemical change.
(c) State the difference between a physical change and a chemical change in terms of the formation of new substances.