Q.3. Answer in a few words only.
1. What do you know about cubit?
2. What is the standard uint of time?
3. What is a habitat ?
4. What is hibernation ?
5. when do we see a shadow ?
6. what is the best reflector of light?
7. Define a battery.
8. What are insulators ?
9. Is magnetite a natural magnet ?
10. Name the three states of water ?
Q.4- Answer in detail.
1. Explain any two sources of water ?
2. How is composting useful ?
3. Describe the composition of air ?
4. Write a few uses of magnet ?
5. Describe the anatomy of a dry cell.
Answers
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1) ➡️ Cubit is the unit of measurement of length based on the length of the forearm, typically the tip of the middle finger to the elbow bottom. This unit of measurement was preferred by Egyptians and Mesopotamians.
2) ➡️ The SI unit of time is the second, which has been further accurately defined as “the time interval equal to 9192631770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom (13th CGPM, 1967).” In any case, the unit second is often represented as s or sec.
3) ➡️ A habitat is a place or an environmental area where animals, plants and other organisms live and depend on their habitat for their food, water, air, shelter and different needs.
4) ➡️ Hibernation is the condition in which the animals go dormant during winters by lowering their metabolic activities. This can be seen in reptiles, fish and amphibians. To combat the problem of food shortage during hibernation, these animals eat a lot of food and store in the form of excess fat.
5) ➡️ When it is early morning or late afternoon, you may notice that your shadows are elongated. But at noon, when the sun is right above your head, the shadow formed is short and dark in nature.
6) ➡️ When a ray of light approaches a smooth polished surface and the light ray bounces back, it is called the reflection of light.
7) ➡️ A battery can be defined as an electrochemical device (consisting of one or more electrochemical cells) which can be charged with an electric current and discharged whenever required.Primary batteries can only be charged once. When these batteries are completely discharged, they become useless and must be discarded.
8) ➡️ Insulators are materials that hinder the free flow of electrons from one particle of the element to another.
9) ➡️ Magnets occur naturally as a particular type of rock. This rock is called magnetite.
10) ➡️ Solid water, liquid water, water as a gas