Please select a subject first
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Explain why some fibres are called synthetic.
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Mark (✓) the correct answer:
Rayon is different from synthetic fibres because
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Fill in the blanks with appropriate words.
Synthetic fibres are also called ______ or _______ fibres.
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Fill in the blanks with appropriate words.
Synthetic fibres are synthesised from raw materials called ______
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Give examples which indicate that nylon fibres are very strong.
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Rana wants to buy shirts for summer. Should he buy cotton shirts or shirts made from synthetic material? Advise Rana, giving your reason.
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Match the terms of column A correctly with the phrases given in column B.
| A | B | ||
| 1 | Polyester | a | Prepared by using wood pulp |
| 2 | Teflon | b | Used for making parachutes and stockings |
| 3 | Rayon | c | Used to make non-stick cookware |
| 4 | Nylon | d | Fabrics do not wrinkle easily |
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‘Manufacturing synthetic fibres is actually helping conservation of forests’. Comment.
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Fill in the blanks:
Metals react with acids to produce _________ gas.
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Mark ‘T’ if the statement is true and ‘F’ if it is false.
Generally, non-metals react with acids. ( )
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Mark ‘T’ if the statement is true and ‘F’ if it is false.
Sodium is a very reactive metal. ( )
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Mark ‘T’ if the statement is true and ‘F’ if it is false.
Copper displaces zinc from zinc sulphate solution. ( )
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Give reasons for the following.
Copper cannot displace zinc from its salt solution.
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Give reasons for the following.
Sodium and potassium are stored in kerosene.
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What happens when Dilute sulphuric acid is poured on a copper plate?
Write word equations of the reactions involved.
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What happens when Iron nails are placed in copper sulphate solution?
Write word equations of the reactions involved.
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Saloni took a piece of burning charcoal and collected the gas evolved in a test tube.
(a) How will she find the nature of the gas?
(b) Write down word equations of all the reactions taking place in this process.
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In an experiment 4.5 kg of a fuel was completely burnt. The heat produced was measured to be 180,000 kJ. Calculate the calorific value of the fuel.
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Can the process of rusting be called combustion? Discuss.
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Protected forests are also not completely safe for wild animals. Why?
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