Science 3 Marks Question

Read the following story titled ‘Eco-friendly Prithin’, and tick the most appropriate option(s) given in the brackets. Provide a suitable title of your choice for the story.
Prithvi is preparing a meal in the kitchen. He chops vegetables, peels potatoes, and cuts fruits (physical changes/chemical changes). He collects the seeds, fruits, and vegetable peels into a clay pot (physical change/ chemical change). The fruits, vegetable peels, and other materials begin to decompose due to the action of bacteria and fungi, forming compost (physical change/chemical change). He decides to plant seeds in the compost and water them regularly. After a few days, he notices that the seeds begin to germinate and small plants start to grow, eventually blooming into colourful flowers (physical change/chemical change). His efforts are appreciated by all his family members.

Table : Can changes be reversed?

Change	The original state can be brought back (Yes/ No)
Melting ice cubes
Chopping vegetables
Boiling water
Making popcorn from corn
Cutting a piece of paper
Adding beetroot extract to water
Burning wood
Diying wet clothes
Making small balls of dough
Rolling small balls of dough into chapatis
Cooking of food
Making pot from mud

A cleaned magnesium ribbon about 3-4 cm long is burnt using a burner by holding it with a pair of tongs and the ash so formed is collected in a watch-glass. The magnesium ribbon is kept away as far as possible from eyes.
Q.1. What is the colour of the powder collected in a watch glass ?
Q.2. Write the changes that determines the occurrence of chemical reaction.
Q.3. What is the chemical name of the powder collected in a watch glass ?

Is air essential for combustion? Explain with the help of an activity.

Observe the following figure and answer the following questions:

(i) What does this figure show?
(ii) Name the gas released.
(iii) Write the effect of the gas on lime water.
(iv) Write the chemical equation of the reaction.

Explain weathering of rocks.

If you leave a piece of iron in the open for a few days, it acquires a film of brownish substance, called rust.
(a) Do you think rust is different from iron?
(b) Can you change rust back into iron by some simple method?
(c) Do you think formation of rust from iron is a chemical change?
(d) Give two other examples of a similar type of change.

Which gas is released when vinegar and baking soda are mixed? What happens when this gas is passed through lime water?

These students are describing some changes. What kinds of changes are they talking about?

Draw a pictorial presentation of the process of rusting and explain the chemical changes involved.

Research famous scientists (e.g., Marie Curie, Antoine Lavoisier) and their contributions to the understanding of chemical reactions and changes. Create a timeline or a presentation about the history of chemical discoveries.

Create a collage of natural changes that include both physical and chemical changes, such as the melting of ice, the rusting of metals, the decay of food, and the growing of plants.