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- Question
Parasec is ythe unit of
Options- A. distance
- B. time
- C. intensity of light
- D. magnetic line
- Correct Answer
- distance
- 1. What kind of crystalline solid is graphite?
Options- A. Metallic
- B. Ionic
- C. Molecular
- D. Covalent- network Discuss
- 2. What color does blue and yellow make?
Options- A. Green
- B. Black
- C. Red
- D. White Discuss
- 3. Which is a common first indicator of an approaching thunderstorm?
Options- A. too hot
- B. heavy wind
- C. a buildup of dark clouds
- D. lightning Discuss
- 4. How can we measure specific gravity of milk?
Options- A. Using a viscometer
- B. Using an odometer
- C. Using a hygrometer
- D. Using a hydrometer Discuss
- 5. Weight of a person at a height of 2R from the centre of the earth, where R is the radius of the earth _______.
Options- A. remains same
- B. becomes half
- C. becomes twice
- D. becomes one-fourth Discuss
- 6. Heat is associated with
Options- A. K.E of random motion of molecules
- B. K.E of orderly motion of molecules
- C. Total K.E of random and orderly motion of molecules
- D. None of these Discuss
- 7. Why does the sea appear blue in colour?
Options- A. Reflection of the sun light from water surface
- B. Interference of the sun light from water surface
- C. Scattering of the sunlight by water molecules
- D. refraction of the sun light Discuss
- 8. A boy sitting in a train moving with a uniform velocity drops a coin outside. A man standing outside the train will find the trajectory of the coin to be
Options- A. a parabola
- B. a circle
- C. a horizontal straight line
- D. a vertical straight line Discuss
- 9. Max well is the unit of
Options- A. intensity of magnetization
- B. permeability
- C. magnetic flux
- D. magnetic susceptibility Discuss
- 10. A man stands in a lift which accelerates upwards. The resultant reaction force on the floor of the lift is
Options- A. greater than the weight of the man
- B. less than the weight of the man
- C. Same as the weight of the man
- D. Zero Discuss
Physics problems
Search Results
Correct Answer: Covalent- network
Explanation:
Graphite is a covalent-network type of crystalline solid.
There are two main categories of solids.
1. Crystalline solids and
2. Amorphous solids.
Crystalline solids are those in which the atoms, ions, or molecules that make up the solid exist in a regular, well-defined arrangement.
There are four types of crystalline solids :
Ionic solids :? Made up of positive and negative ions and held together by electrostatic attractions. They?re characterized by very high melting points and brittleness and are poor conductors in the solid state. An example of an ionic solid is table salt, NaCl.
Molecular solids :? Made up of atoms or molecules held together by London dispersion forces, dipole-dipole forces, or hydrogen bonds. Characterized by low melting points and flexibility and are poor conductors. An example of a molecular solid is sucrose.
Covalent-network (also called atomic) solids :? Made up of atoms connected by covalent bonds; the intermolecular forces are covalent bonds as well. Characterized as being very hard with very high melting points and being poor conductors. Examples of this type of solid are diamond and graphite, and the fullerenes. As you can see below, graphite has only 2-D hexagonal structure and therefore is not hard like diamond. The sheets of graphite are held together by only weak London forces!
Metallic solids :? Made up of metal atoms that are held together by metallic bonds. Characterized by high melting points, can range from soft and malleable to very hard, and are good conductors of electricity.
Correct Answer: Green
Correct Answer: a buildup of dark clouds
Explanation:
The first indicator of an approaching thunderstorm is a buildup of dark clouds.
A thunderstorm is a storm with lightning and thunder; it is usually produced by heavy rain, gusty wind, and the cumulonimbus cloud. The thunderstorm is made up of moisture, unstable air and lift.
Correct Answer: Using a hydrometer
Correct Answer: becomes one-fourth
Correct Answer: K.E of random motion of molecules
Correct Answer: Scattering of the sunlight by water molecules
Explanation:
Sea appears blue in colour due to the scattering of the rays when they hit water molecules
Correct Answer: a parabola
Explanation:
Parabola, because when the coin is dropped at a particular point, it has the same velocity as the running train. So by Newton's first law, it continues its motion horizontally with that velocity. But then, it is also pulled down by earth's gravity continuously. In this situation its horizontal motion gives way to the parabolic motion until it reaches the ground.
Correct Answer: magnetic flux
Correct Answer: greater than the weight of the man
Explanation:
The weight of the man mg is acting on the floor. As the lift is moving up with an acceleration, say a, the man too in it is having this acceleration. The force producing this acceleration is ma. By Newton's third law, this force will have an equal reaction pressing the floor equal to ma. Therefore the total resultant reaction on the floor is mg+ma = m(g+a) which is mg, the weight of the man. So (a) is correct.
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