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प्रश्न
Explain the term – ‘sublimation’. Is sublimation of naphthalene – a physical or a chemical change. Give reasons.
उत्तर
It is the conversion of a solid – directly into gaseous (vapour) state and on cooling directly back to solid-state – without changing into a liquid state.
It involves a change of state-and hence it is a physical change.
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संबंधित प्रश्न
What do you observe when :
lighted match stick is brought near the mouth of the test tube containing hydrogen gas.
State whether the following is physical or chemical changes.
lightning —
Which of the following are physical changes ?
- melting of iron metal
- rusting of iron metal
- bending of an iron rod
- drawing a wire of iron metal
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.
Fill in the blank with the correct word of the statement given below:
Sublimation involves a __________ change.
Change is the law of nature which occurs in everyday life.
State when a substance [i.e. matter] undergoes a kind of change.
Compare the energy changes involved during a physical and a chemical change.
Filling up a balloon with hot air is a _______ change.
The change of state of a substance from solid to liquid and liquid to gas is ______.
Keeping a stone in sunlight for few hours is ______.
