State two different between physical and chemical change. Why is rusting considered as a chemical change? Is dissolving sugar in water chemical or physical change? Explain. State three signs that a chemical change has occured.

Here are the answers to your questions:

1. State two differences between physical and chemical change.

• In a physical change, no new substances are formed, only the form or appearance of the substance changes. In a chemical change, new substances with different properties are formed.
• Physical changes are often easily reversible (e.g., melting ice can be refrozen). Chemical changes are generally irreversible (e.g., burning wood cannot be turned back into wood).

2. Why is rusting considered a chemical change?

Rusting is considered a chemical change because it involves the formation of a new substance, iron oxide (rust), from iron and oxygen in the presence of water. The original iron is transformed into a different compound with new chemical properties, and this process is generally irreversible.

3. Is dissolving sugar in water a chemical change or a physical change? Explain.

Dissolving sugar in water is a physical change. This is because the sugar molecules themselves do not change their chemical composition; they are simply dispersed throughout the water. No new substance is formed, and the sugar can be recovered by evaporating the water, demonstrating its reversibility.

4. State THREE signs that a chemical change has occurred.

Three signs that a chemical change has occurred are:

• Change in color (e.g., fruit ripening).
• Formation of a gas (often seen as bubbles).
• Change in temperature (heat is either absorbed or released).