Which of the following are chemical changes?
(i) Decaying of wood
(ii) Burning of wood
(iii) Sawing of wood
(iv) Hammering of a nail into a piece of wood
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (i) and (iv)
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Which of the following are chemical changes? (a)Growth of a plant (b)Rusting of iron
Following are Chemical changes. (a)Growth of a plant (b)Rusting of iron (c) Cooking of food (d)Digestion of food (e) Burning of a candle.
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Fill in the blanks: (a) Burning of wood and coal causes _________of air. (b) A liquid fuel used in homes is ___________.
(a) Burning of wood and coal causes pollution of air. (b) A liquid fuel used in homes is LPG. (c) Fuel must be heated to its ignition temperature before it starts burning. (d)...
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which among the following are physical or chemical changes?
(a) physical change (b)chemical change (c) physical change (d)chemical change (e) physical change
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Classify the changes involved in the following processes as physical or chemical changes:
Physical Changes: (b) Dissolving sugar in water, (d) Melting of wax, (e) Beating Aluminium to make Aluminium foil. Chemical Changes: (a) Photosynthesis, (c) Burning of coal, (f) Digestion of food
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When a candle burns, both physical and chemical changes take place. Identify these changes.
Physical Changes: On heating, candle wax gets melted is a physical change. Since it again turns into solid wax on cooling. Chemical Changes: The wax near to flame burns and gives...
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Explain why burning of wood and cutting it into small pieces are considered as two different types of changes.
Burning of wood is a chemical change because wood on burning converted to new substances like ash (carbon), carbon dioxide gas, water vapour, heat and light. The change is irreversible....
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Why is charcoal considered a better fuel than wood? What are the disadvantages of converting wood into charcoal?
Charcoal is considered a better fuel than wood because: (i) It has high calorific value. (ii) It does not produce any smoke. Disadvantages: (i) 1 kg of wood on destructive distillation produces only 0.25...
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Though wood is a renewable source of energy, but the use of wood as a fuel is not a wise decision. Explain.
Wood is a renewable source of energy. It is obtained by cutting trees. A new plant sapling usually takes more than 15 years to grow and mature into a tree....
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Which among the following are physical or chemical changes? i. Evaporation of petrol
Physical changes: Evaporation of petrol, heating of an iron rod to red hot, sublimation of solid ammonium chloride. Chemical changes: Burning of Liquefied Petroleum Gas (LPG), curdling of milk.
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How is charcoal obtained from wood? Why is charcoal considered a better fuel than wood?
Charcoal is obtained from wood by destructive distillation of wood. Charcoal is considered a better fuel than wood because (i) it has higher calorific value than wood. (ii) it does not produce...
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