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प्रश्न
Give three reasons why melting of wax, is considered a physical change while burning of a candle, a chemical change.
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उत्तर
Melting of wax is a temporary and reversible change on cooling, wax solidifies, and no new product is formed while burning of a candle is a permanent change i.e. products are not convertible, a new substance is formed having different composition & different properties.
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संबंधित प्रश्न
Classify the following as chemical or physical change:
Cutting of trees
Tick the most appropriate answer
2. Melting of ice is a
- reversible change
- irreversible change
- chemical change
- none of these
Classify the following changes as physical or chemical:- melting of a solid (wax)
Fill in the blank.
When a candle burns, wax melts. Melting of wax is a ________ change.
Write true or false
Burning of sugar is a temporary change.
Which of the following are chemical changes ?
- decaying of wood
- burning of wood
- sawing of wood
- hammering of nail into wood
Read the paragraph and note down the various types of changes it mentions.
It was nearing six o'clock in the evening. The sun was setting. A breeze was blowing. Leaves on the tree were shaking. Sahil was sitting in the courtyard, rolling balls of wet soil, and shaping them into various toys. Then he felt hungry and went into the house. Mother made a dough from wheat flour and fried purees. While eating hot purees, his attention was drawn outside the window. It had started raining. There was lightning, too. Sahil was enjoying his dinner in the dim light.
State which of the following terms connected with change of state of matter i.e.
(a) Melting
(b) Vaporisation
(c) Condensation
(d) Freezing
pertain to –
- Conversion of a liquid into a vapour or gas.
- Conversion of a liquid into a solid.
- Conversion of a solid into a liquid on heating.
Natural changes which take place in nature on their own, are beyond the control of human being.
Water is the universal solvent. Why?
