I.
Short-answer type questions (I):
1. Classify the following into physical or chemical changes.
(a) Crystallisation of common salt
(b) Burning of incense stick
(c) Cooking of food
(d) Tearing of cloth
2. Define a physical change. Mention two examples of this change.
3. Why does iron rust? How can it be prevented? Describe two methods to prevent rusting,
5. (a) What is galvanisation? Why is it done?
(b) How does painting an iron grill prevent rusting of the grill?
J
Answers
1 .chemical change
2 .physical change
3 .physical change
4 .physical change
5. Physical changes are changes affecting the form of a chemical substance, but not its chemical composition. Physical changes are used to separate mixtures into their component compounds, but can not usually be used to separate compounds into chemical elements or simpler compounds eg ; boiling and freezing
6.Rusting is an oxidation reaction. The iron reacts with water and oxygen to form hydrated iron(III) oxide, which we see as rust.
Here is the word equation for the reaction:
iron + water + oxygen → hydrated iron(III) oxide
Iron and steel rust when they come into contact with water and oxygen – both are needed for rusting
eg: by galvanisation by paint
7.galvanisation is a process of of applying a protective zinc coating to steel or iron, to prevent rusting. the most common method is hot-dip galvanizing,
8.an iron grill painted frequently to prevent for rusting.
iron can rust up the metal due to which iron grill painted frequently to prevent its contact from oxygen present it the air
explanation
mark me brainliest
Answer:
i donot know
Explanation: