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प्रश्न
Give the reason why the following is considered as chemical changes.
A bright light is seen evolved when a strip of magnesium is heated.
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उत्तर
Magnesium is heated producing a bright light to form MgO in the air is a chemical change as the composition changes (MgO white powder) is formed, is irreversible. We cannot get magnesium back from MgO.
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संबंधित प्रश्न
State whether the following is physical or chemical changes.
glowing of a bulb -
A physical change is temporary. Explain.
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.
Which of the following are physical changes and which are chemical changes ?
Glowing of an electric bulb
Photosynthesis is a natural process by which green plants manufacture food in the presence of sunlight.
State the conclusions which can be drawn, to represent photosynthesis as a physical or a chemical change.
Is a change of state of matter – a physical or a chemical change. Give reasons.
State which of the following 1 to 5 pertain to – A: Physical Change B: Chemical change :
- Sublimation.
- Fermentation.
- Liquefaction or condensation.
- Magnetization.
- Respiration.
In a solution of salt in water, water is the solute
Give an example of a physical change in which the color of the substance changes.
Explain the characteristics of physical change with examples.
