1. Burning of an incense stick is which type of change?
2. Freezing of water is which type of change?
3. Formation of biogas from cowdung is which type of change?
4. Bursting of a balloon is which type of change?
5. Heating of sugar in a pan is which type of change?
6. Lighting of electric bulb is which type of change?
Answers
Answer:
When an incense stick is burnt new substances ash and smoke are produced. The incense stick cannot be produced from the residues again. Hence it is a chemical change because it goes through a chemical reaction and is irreversible while physical changes are reversible.
Only a change in state (from liquid to solid) takes place during the freezing of water to form ice, but no new substance is formed. So, the freezing of water (to form ice) is a physical change.
The waste generated from kitchen and sewage from the hostels is given as feedstock to produce 600 m3 of biogas per day with cow dung as byproduct. The methane gas generated from Biogas is purified and this is used for power generation
1. When an incense stick is burnt new substances ash and smoke are produced. The incense stick cannot be produced from the residues again. Hence it is a chemical change because it goes through a chemical reaction and is irreversible while physical changes are reversible
2. Physical changes alter only the size, shape, form or matter state of a material. Water boiling, melting ice, tearing paper, freezing water
3. Production of biogas is a chemical change . Because in biogas plant many gases released from cow dung and other animal waste . These gases react with each other chemically to produce biogas.
4. It is a physical change because there is an increase in air pressure inside the balloon. When the balloon bursts then it becomes small in respect to when it was having air inside it.
5. It's a chemical change because sugar reacts with the heat energy. It is a chemical reaction.
6. Glowing of a bulb is a physical change. When electric current is passed through the bulb, the filament starts glowing and the glow stops as soon as we stop the current. Here, the change is temporary ,no new products are formed and there is no chemical change in the tungsten of the filament.