Answer the following questions
1. Paheli bought a statue made up of copper. To her surprise, it acquired a dull green coating after a couple of months. Explain the reason.
2. Name the non-metal that is stored in water and why?
3. A girl is pushing a box towards East direction. In which direction should her friend push the box so that it moves faster in the same direction and why? What value do you learn from her friends" action?
4. If wheat is sown in kharif season, what would happen? Explain.
5. Define a) Fermentation b) Harvesting
6. What are preservatives? Write any two examples of chemical preservatives.
Answers
Answer:
1) Due to corrosion, the copper plate becomes dull green after a couple of months, because, when copper comes in contact with moisture and CO2, it reacts to form a green mixture that is copper hydroxide and copper carbonate.
2) The melting point of phosphorus is very low which is around 440 degreeC which is why it easily catches fire in the atmospheric condition, due to which, phosphorus is stored in water. Hence, non-metal which is stored in water is Phosphorus.
3) Her friend should push the box towards the East. Her friend should do so because both of them would be applying the force in the same direction, and so the resultant force will be more.
4) If wheat is sown in the kharif season (from June to October), then the crop might get destroyed because of many factors such as lack of optimum temperature, adaptability, availability of pests, etc. Kharif season includes the rainy season, which is not favorable for the growth of the wheat crop.
5) a) Fermentation is defined as the extraction of energy from carbohydrates in the absence of oxygen.
b) Harvesting is the process of gathering a ripe crop from the fields.
6) Preservatives are specific ingredients added to foods and food packaging that allows the food to remain safe, fresh, and edible for a long time. Some chemical preservatives include benzoic acid, sorbic acid, sulfur dioxide, nitrates and more.
Hope this helped.