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Question
Solve this crossword by using the clues that follow-
Across
1. Energy in the form of sunlight is absorbed by the green plants in this process.
4. The reddish-brown substance formed over iron in the presence of oxygen and moisture.
5. This change is permanent and irreversible.
6. The process in which a solid directly changes into gaseous state.
Down
1 . It is the change that takes place in case of swinging pendulum of a clock. –
2. Occurrence of this is a non-periodic change as well as a natural change.
3. It is a physical change.
Solution
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5. Photosynthesis requires
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- wind energy
- sunlight.
- sound energy
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change in which the substance can be brought back to its original state is called a ............... change.
Write true or false for the statement
Decomposition of leaves is a fast change.
Classify the following changes as physical or chemical:- melting of a solid (wax)
True or false
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Differentiate between the following change with a suitable example.
Periodic and non-periodic change
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State whether the following statement is true or false. If false write the correct statement.
Melting of ice is an exothermic, irreversible chemical change.
Select the correct answer from the choice given below to complete the sentence
The dissolution of lead nitrate in water is deemed as a _________ change.
Two drops of dilute sulphuric acid were added to 1 g of copper sulphate powder and then a small amount of hot water was added to dissolve it (step I). On cooling, beautiful blue coloured crystals got separated (step II). Step I and Step II are:
