Answer the following Questions:
1. What are the two factors on which friction depend?
2. State the two laws of reflection.
3. Give the name of a few sources that are rich in Vitamin A
4. Define the term calorific value
5. What are called as Metalloids?
6. What are the conditions necessary for combustion?
7. Write the differences between external and internal fertilization with
examples
8. Name the chemicals used for the disinfection of water
9. What are called as Hormones?
Answers
Answer:
1)Friction depends on the smoothness or roughness of the two surfaces which are in contact.
A rough surface produces greater friction as compared to a smooth surface.
2)Laws of reflection: The first law of reflection states that the incident ray, the reflected ray, and the normal to the surface of the mirror, all lie in the same plane. The second law of reflection states that the angle of reflection is equal to the angle of incidence.
3)The top food sources of vitamin A in the U.S. diet include dairy products, liver, fish, and fortified cereals; the top sources of provitamin A include carrots, broccoli, cantaloupe, and squash
Answer:
answer no.1
Friction depends on two factors: (i) Nature of the surfaces in contact i.e. whether surface is rough or smooth.
Friction depends on the smoothness or roughness of the two surfaces which are in contact.
A rough surface produces greater friction as compared to a smooth surface.
answer no.2
Laws of reflection: The first law of reflection states that the incident ray, the reflected ray, and the normal to the surface of the mirror, all lie in the same plane. The second law of reflection states that the angle of reflection is equal to the angle of incidence.
answer no.3
The top food sources of vitamin A in the U.S. diet include dairy products, liver, fish, and fortified cereals; the top sources of provitamin A include carrots, broccoli, cantaloupe, and squash.
answer no.4
the energy contained in a fuel or food, determined by measuring the heat produced by the complete combustion of a specified quantity of it. This is now usually expressed in joules per kilogram.
answer no.5
A metalloid is an element that has properties that are intermediate between those of metals and nonmetals. Metalloids can also be called semimetals. On the periodic table, the elements colored yellow, which generally border the stair-step line, are considered to be metalloids.
answer no.6
Three things are required in proper combination before ignition and combustion can take place---Heat, Oxygen and Fuel. There must be Fuel to burn. There must be Air to supply oxygen. There must be Heat (ignition temperature) to start and continue the combustion process.
answer no.7
Internal fertilization is the process when the syngamy (union of male and female gamete) occurs inside the female body after insemination using copulation. In contrast, External fertilization is the syngamy outside the female body, that is in the outer environment especially in water bodies.
answer no.8
The three chemicals most commonly used as primary disinfectants are chlorine, chlorine dioxide and ozone. Monochloramine, usually referred to as chloramine, is used as a residual disinfectant for distribution.
answer no.9
Hormone: A chemical substance produced in the body that controls and regulates the activity of certain cells or organs. Many hormones are secreted by special glands, such as thyroid hormone produced by the thyroid gland.
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