LIGHT:REFLECTION AND REFRACTION-II:BRIEF ANSWERS

ANSWER IN BRIEF

*INDEX-TOPIC SEARCH

1. EXPLAIN THE NATURE OF LIGHT IN BRIEF
   

   ANS:
   

   • Light is an electromagnetic radiation in the form of waves and it does not require material medium for its propagation.
   • Light travels at the speed of 3 x 10⁸ m/s in vacuum.
   • When it passes through a transparent medium its speed reduces significantly.
   • The wavelength of visible light is 4 x 10^(-7) to 8 x 10^(-7) m.
   • Light incident on a surface separating two media is partly reflected, partly refracted(transmitted), and partly absorbed.
   • Highly polished surface reflects a large amount of incident light whereas a transparent medium refracts(transmits) most of the light incident on it.
   • A lens or mirror focuses light falling on it because of reflection or refraction.
   • Due to reflection by a mirror or refraction by a lens, the image of an object is formed or it appears to have formed.
   
   



2. EXPLAIN:REGULAR AND IRREGULAR REFLECTION
   

   ANS:When light is incident on an opaque surface,reflection occurs.There are two types of reflection:(i)Regular reflection and (ii)Irregular reflection.
   
   
   
   Regular Reflection:When a parallel beam of light falls on a smooth or highly polished (opaque) surface, the reflected beam is also parallel and directed in a fixed direction.This type of reflection is called regular reflection.For example,reflection by a mirror. Regular reflection does not enable us to see the object.
   
   Irregular Reflection:When a parallel beam of light falls on a rough surface, the reflected beam is not parallel and it spreads over a wide area. This is called irregular reflection.Irregular reflection enables us to see the object.
   



3. STATE LAWS OF REFLECTION
   

   ANS:The laws of reflection are:
   
   

   • The angle of incidence(θ_i) is equal to the angle of reflection(θ_r).
   
   
   • The incident ray, the normal to the mirror at the point of incidence and the reflected ray, all lie in the same plane.
   
   



4. EXPLAIN : Real image and virtual image.
   

   ANS:
   
   

   
   
5. MENTION CHARACTERISTICS OF IMAGE FORMED BY A PLANE MIRROR.
   

   ANS:

   
   
   • The image is virtual, erect and of the same size as the object.
   • The image is at the same distance behind the mirror as the object is in front of the mirror.
   • The image is laterally inverted,i.e., when a person raises the left hand the image appears to raise the right hand.
     

   
   

   
   
6. Draw the ray diagram to show the position, nature and the size of the image when object is placed at infinity from a concave mirror.
   

   ANS:
   
   
   
   The image is formed at focus(F); it is real, inverted and highly diminished.



7. Draw the ray diagram to show the position, nature and the size of the image when object is placed beyond C (Center of curvature) of a concave mirror.
   

   ANS:
   
   
   
   The image is formed between focus(F) and center of curvature(C); it is real, inverted and diminished.



8. Draw the ray diagram to show the position, nature and the size of the image when object is placed at C (Center of Curvature)of a concave mirror.
   

   ANS:
   
   
   
   The image is formed at C; it is real, inverted and of the same size as the object.



9. Draw the ray diagram to show the position, nature and the size of the image when object is placed between C and F of a concave mirror.
   

   ANS:
   
   
   
   The image is formed beyond C; it is real, inverted and enlarged.



10. Draw the ray diagram to show the position, nature and the size of the image when object is placed at focus(F) of a concave mirror.
    

    ANS:
    
    
    
    The image is formed at infinite distance; it is real, inverted and highly enlarged.



11. Draw the ray diagram to show the position, nature and the size of the image when object is placed between pole(P) and F of a concave mirror.
    

    ANS:
    
    
    
    The image is formed behind the mirror; it is virtual and erect and enlarged.



12. Draw the ray diagram to show the position, nature and the size of the image when object is placed at infinity from a convex mirror.
    

    ANS:
    
    
    
    The image is formed at the focus F behind the mirror; it is virtual and erect and highly diminished.



13. Draw the ray diagram to show the position, nature and the size of the image when object is placed between pole(P) of a convex mirror and infinity.
    

    ANS:
    
    
    
    The image is formed between P and F behind the mirror; it is virtual and erect and diminished.



14. Draw the ray diagram to show the position, nature and the size of the image when object is placed at infinity from a convex lens.
    

    ANS:
    
    
    The image is formed on the opposite side of lens at focus (F₂); it is real and inverted and highly diminished(point-sized).



15. Draw the ray diagram to show the position, nature and the size of the image when object is placed beyond 2F₁ of a convex lens.
    

    ANS:
    
    
    
    The image is formed between F₂ and 2F₂of the lens; it is real, inverted and diminished.



16. Draw the ray diagram to show the position, nature and the size of the image when object is placed at 2F₁ of a convex lens.
    

    ANS:
    
    
    
    The image is formed at 2F₂; it is real inverted and of same size as the object.



17. Draw the ray diagram to show the position, nature and the size of the image when object is placed between F₁ and 2F₁ of a convex lens.
    

    ANS:
    
    
    
    The image is formed beyond 2F₂; it is real, inverted and enlarged.



18. Draw the ray diagram to show the position, nature and the size of the image when object is placed at F₁ of a convex lens.
    

    ANS:
    
    
    
    The image is formed at infinity; it is real, inverted and highly enlarged.



19. Draw the ray diagram to show the position, nature and the size of the image when object is placed between F₁ and optical center O of a convex lens.
    

    ANS:
    
    
    
    The image is formed on the same side of the lens as the object; it is virtual,erect and enlarged.



20. Draw the ray diagram to show the position, nature and the size of the image when object is placed at infinity from a concave lens.
    

    ANS:
    
    
    
    The image is formed at the focus F₁ on the same side of the object; it is virtual, erect and highly diminished.



21. Draw the ray diagram to show the position, nature and the size of the image when object is placed between infinity and the optical center O of a concave lens.
    

    ANS:
    
    
    
    The image is formed between focus F₁ and the optical center O on the same side of the object; it is virtual, erect and diminished.



22. STATE LAWS OF REFRACTION.
    

    ANS:The laws of refraction are:
    
    

    • The ratio of the sine of the angle of incidence(θ₁) to the sine of the angle of refraction(θ₂) is constant.
    
    
    • The incident ray, the normal to the surface separating two mediums and the refracted ray, all lie in the same plane.
    
    



23. DISTINGUISH BETWEEN REFLECTION AND REFRACTION.
    

    ANS:
    
    



24. STATE SNELL'S LAW AND WRITE ITS FORMULA.
    

    ANS:The ratio of the sine of the angle of incidence and the sine of the angle of refraction is always constant for given pair of mediums.
    
    sinΘ₁/sinΘ₂ = constant
    
    The constant is known as the refractive index of medium 2 with respect to medium 1, and is denoted by η₂₁

    
    
25. THE REFRACTIVE INDEX OF TWO MEDIUMS A AND B ARE 1.33 AND 1.5, RESPECTIVELY.
    1. IF A RAY TRAVELS FROM A TO B, WHAT WILL HAPPEN TO ITS SPEED?
    2. WILL TOTAL INTERNAL REFLECTION OCCUR IF A RAY TRAVELS FROM A TO B?
       
    
    

    ANS:

    
    
    1. The speed of the light ray will decrease as it enters a denser medium from a rarer medium.
    2. No, total internal reflection will not occur because the ray will move towards the normal in this case.
       

    
    

LIGHT:REFLECTION AND REFRACTION-I:MCQs AND SHORT ANSWERS

MULTIPLE-CHOICE QUESTIONS

*INDEX-TOPIC SEARCH

SELECT THE CORRECT ALTERNATIVE:

1. The speed of light is_______ in vacuum.
   
   
   
   1. 3 x 10⁵ m/s
      
   2. 3 x 10⁸ m/s
      
   3. 3 x 10⁸ km/s
      
   4. 3 x 10⁶ m/s
      
   
   
2. The wavelength of the visible light is ________.
   
   
   
   1. 4 x 10^(-7) to 8 x 10^(-7) m
      
   2. 4 x 10⁷ to 8 x 10⁷ m
      
   3. 4 x 10^(-7) to 8 x 10^(-7) Å
      
   4. 4 x 10⁷ to 8 x 10⁷ Å
      
   
   
3. We can see objects because of_______
   
   
   
   1. reflection
      
   2. refraction
      
   3. transmission
      
   4. diffraction
      
   
   
4. The image formed by a convex mirror is always________
   
   
   
   1. real
      
   2. enlarged
      
   3. virtual and enlarged
      
   4. diminished
      
   
   
5. As you move an object away from a convex mirror, its image becomes_____ and moves towards______
   
   
   
   1. smaller, infinity
      
   2. smaller, focus
      
   3. enlarged, infinity
      
   4. enlarged, focus
      
   
   
6. For a spherical mirror, ______ is true.
   
   
   
   1. f = 2R
      
   2. R = 2f
      
   3. fR = 2
      
   4. fR = 1/2
      
   
   
7. The mirror formula is ________.
   
   
   
   1. 1/u - 1/v = 1/f
      
   2. 1/f + 1/u = 1/v
      
   3. f = uv/(u+v)
      
   4. f = (u+v)/uv
      
   
   
8. For a plane mirror, magnification (m)=________
   
   
   
   1. 0
      
   2. 1
      
   3. ± 1
      
   4. ≤ 0
      
   
   
9. Magnification for convex mirror is ________.
   
   
   
   1. always positive
      
   2. always negative
      
   3. sometimes positive
      
   4. 1
      
   
   
10. The image formed by a concave lens is ________.
    
    
    
    1. always real and enlarged
       
    2. always real and diminished
       
    3. always virtual and enlarged
       
    4. always virtual and diminished
       
    
    
11. The lens formula is ________.
    
    
    
    1. 1/f = 1/u + 1/v
       
    2. 1/f = 1/u - 1/v
       
    3. 1/f = 1/v - 1/u
       
    4. 1/f + 1/v = u
       
    
    
12. 1 diopter = ________.
    
    
    
    1. 1 m
       
    2. 1 m^(-1)
       
    3. 1 cm
       
    4. 1 cm^(-1)
       
    
    
13. Which of the following is a true statement?
    
    
    
    1. The power of a lens is always positive.
       
    2. The power of a lens is always negative.
       
    3. The power of a convex lens is positive.
       
    4. The power of a concave lens is positive.
       
    
    
14. Image formed by a concave mirror is erect and enlarged.What is the position of the object?
    
    
    
    1. Between focus F and the center of curvature
       
    2. At the center of curvature
       
    3. Beyond the center of curvature
       
    4. Between pole and the focus
       
    
    
15. If the focal length of a spherical mirror is 40 cm, then its radius of curvature is _______ cm.
    
    
    
    1. 80
       
    2. 20
       
    3. 10
       
    4. 5
       
    
    
16. The velocity of light in vacuum is _______ ms^(-1)
    
    
    
    1. 3 x 10⁶
       
    2. 3 x 10⁸
       
    3. 3 x 10 ¹²
       
    4. 3 x 10¹⁵
       
    
    
17. If the angle of incidence, θ_i = 0°, the angle of reflection, θ_r = ________.
    
    
    
    1. 0°
       
    2. 90°
       
    3. 180°
       
    4. 45°
       
    
    
18. No matter how far is the object from the mirror, the image of the object appears erect. The mirror is ________.
    
    
    
    1. concave
       
    2. convex
       
    3. either concave or convex
       
    4. none of these
       
    
    
19. A boy is standing at a distance of 2 m in front of a plane mirror.The distance between the boy and his image is ________ m.
    
    
    
    1. 4
       
    2. 3
       
    3. 2
       
    4. 1
       
    
    
20. The image formed by a concave mirror is real, inverted and of the same size as that of the object.The position of the object should be ________.
    
    
    
    1. beyond the center of curvature of mirror
       
    2. between the center of curvature and the focus
       
    3. at the center of curvature of the mirror
       
    4. at the focus
       
    
    
21. Which of the following has the highest refractive index?
    
    
    
    1. Glass
       
    2. Water
       
    3. Pearl
       
    4. Diamond
       
    
    
22. Absolute refractive index of any medium is always _______.
    
    
    
    1. 1
       
    2. > 1
       
    3. < 1
       
    4. 0
       
    
    
23. The image formed by a plane mirror is ______.
    
    
    
    1. real
       
    2. diminished
       
    3. enlarged
       
    4. laterally inverted
       
    
    
24. The incident ray passing through the focus(F) of a mirror ______ after reflection.
    
    
    
    1. passes through C
       
    2. passes through F
       
    3. becomes parallel to the principal axis
       
    4. passes through the pole
       
    
    
25. The incident ray passing through the center of curvature(C) of a mirror ______ after reflection.
    
    
    
    1. passes through C
       
    2. passes through F
       
    3. passes through the pole
       
    4. becomes parallel to the principal axis
       
    
    
26. The incident ray parallel to the principal axis of a mirror ______ after reflection.
    
    
    
    1. passes through C
       
    2. passes through F
       
    3. passes through the pole
       
    4. reverts back in the opposite direction
       
    
    
27. According to the sign convention, the distance of object...
    
    
    
    1. is always positive
       
    2. is always negative
       
    3. may be positive or negative
       
    4. is equal to object height
       
    
    
28. According to the sign convention, the distance of image...
    
    
    
    1. is always positive
       
    2. is always negative
       
    3. may be positive or negative
       
    4. is equal to image height
       
    
    
29. The refractive index of a denser medium with respect to a rarer medium is...
    
    
    
    1. 1
       
    2. greater than 1
       
    3. smaller than 1
       
    4. negative
       
    
    
30. The refractive index of a rarer medium with respect to a denser medium is...
    
    
    
    1. 1
       
    2. greater than 1
       
    3. smaller than 1
       
    4. negative
       
    
    
31. Total internal reflection will occur if the angle of reflection is...
    
    
    
    1. 45°
       
    2. 60°
       
    3. 90°
       
    4. 99°
       
    
    
32. Magnification for ______ image is always ______.
    
    
    
    1. real, positive
       
    2. real, negative
       
    3. virtual, negative
       
    4. any, negative
       
    
    
33. If magnification is +1.5, the image is______.
    
    
    
    1. erect
    2. diminished
    3. real
    4. inverted
       
    
    

ANSWERS TO MCQs:

(1) B (2) A (3) A (4) D (5) B (6) B (7) C (8) B (9) A (10) D (11) C (12) B (13) C (14) D (15) A (16) B (17) A (18) B (19) A (20) C (21) D (22) B (23) D (24) C (25) A (26) B (27) B (28) C (29) B (30) C (31) D (32) B (33) A

SHORT ANSWERS

1. What is light?
   
   

   ANS:Light is an electromagnetic radiation which produces sensation in our eyes.

   
   
2. What is the range of wavelength of visible light in Å units ?
   

   ANS:4000 to 7000 Å
   

   
   
3. Which waves do not require material medium for propagation?
   
   

   ANS: Electromagnetic waves do not require material medium for propagation.

   
   
4. What happens to the speed of light when it passes through a transparent medium?
   
   

   ANS: The speed of light is reduced significantly when it passes through a transparent medium.

   
   
5. What happens to light when it is incident on the surface separating two mediums ?
   

   ANS:A part of the incident light is reflected, a part is transmitted and rest is absorbed.
   

   
   
6. Define: Ray of light.
   

   ANS: A straight line path joining one point to another in the direction of propagation of light is known as a ray.

   
   
7. What is a beam of light?
   

   ANS: A bundle of light rays is called a beam of light.

   
   
8. Which phenomena enable the focusing of light by lens and mirrors?
   

   ANS:Refraction and reflection are the phenomena which enable the focusing of light by lens and mirror.

   
   
9. What is an image?
   

   ANS:Whan a number of rays starting from a point meet at another point after reflection or refraction, the second point is called the image of the first point.

   
   
10. Define: Real image.
    

    ANS:When the rays emerging from one point meet really at another point after reflection or refraction, the image formed is called real image.

    
    
11. What is virtual image?
    

    ANS:When the rays emerging from one point appear to meet, when extended backwards, after reflection or refraction, the image formed is virtual image.

    
    
12. Mention two kinds of reflection.
    

    ANS:Regular reflection and Irregular(diffused) reflection are the two kinds of reflection.

    
    
13. Which type of surfaces produce regular reflection?
    

    ANS:Smooth and highly polished surfaces produce regular reflection.

    
    
14. Which type of surface produces irregular reflection?
    

    ANS:Rough surface produces irregular reflection.

    
    
15. What is 'incident angle'?
    

    ANS:The angle that the incident ray makes with the normal is known as incident angle(or Angle of incidence).

    
    
16. What is 'reflection angle'?
    

    ANS:The angle that the reflected ray makes with the normal is known as reflection angle (or Angle of reflection).

    
    
17. How are curved mirrors formed?
    

    ANS:Curved mirrors are formed by cutting circular cross-section of spherical shell.

    
    
18. Define: Radius of curvature of a mirror.
    

    ANS:The radius of the spherical shell from which the mirror is made is called the radius of curvature of a curved mirror.

    
    
19. Define: Centre of curvature of a mirror.
    

    ANS:The center of the spherical shell from which the mirror is made is called the centre of curvature of the mirror.

    
    
20. Define: Pole of a mirror.
    

    ANS:The centre of the reflecting surface is called pole of the mirror.

    
    
21. What is the Principal axis of mirror?
    

    ANS:The imaginary line passing through the pole and the centre of curvature is called the principal axis of mirror.

    
    
22. Define: Aperture of mirror.
    

    ANS:The diameter of the reflecting surface is called aperture of mirror.

    
    
23. Define:Principal focus of a mirror.
    

    ANS:The point where the rays parallel to the principal axis meet or appear to meet after reflection is called the principal focus of the mirror.

    
    
24. Define:The focal length of mirror.
    

    ANS:The distance between the pole and the principal focus of a mirror is called the focal length of mirror.

    
    
25. What is the position, nature and size of the image formed by a concave mirror when the object is at infinity?
    

    ANS:The image is formed at focus; it is real, inverted and highly diminished.

    
    
26. What is the position, nature and size of the image formed by a concave mirror when the object is beyond the center of curvature of the mirror?
    

    ANS:The image is formed between the focus and the center of curvature; it is real, inverted and diminished.

    
    
27. What is the position, nature and size of the image formed by a concave mirror when the object is at C, the center of curvature of the mirror?
    

    ANS:The image is formed at the center of curvature; it is real, inverted and of the same size as the object.

    
    
28. What is the position, nature and size of the image formed by a concave mirror when the object is between C and F?
    

    ANS:The image is formed beyond C; it is real, inverted and enlarged.

    
    
29. What is the position, nature and size of the image formed by a concave mirror when the object is at F?
    

    ANS:The image is formed at infinite distance; it is real, inverted and highly enlarged.

    
    
30. What is the position, nature and size of the image formed by a concave mirror when the object is between pole and F?
    

    ANS:The image is formed behind the mirror; it is virtual, erect and enlarged.

    
    
31. Define: Magnification.
    

    ANS:The ratio of the height of the image to the height of the object is called magnification.

    
    
32. Define: Refraction.
    

    ANS:The change in the direction of a ray of light when it enters from one transparent medium to another transparent medium is called refraction.

    
    
33. Define: Optical center of a lens.
    

    ANS:Optical center of a lens is the center of lens on the principal axis.

    
    
34. Define: Radius of curvature of lens.
    

    ANS:The radii of spheres whose parts form the lens surfaces are called radii of curvature of lens.

    
    
35. Define: Principal focus of convex lens.
    

    ANS:The point of convergence of the rays parallel to principal axis on the principal axis is called the principal focus of a convex lens.

    
    
36. Define: Focal length of lens.
    

    ANS:The distance between the optical center and the principal focus is called the focal length of lens.

    
    
37. Mention the position, nature and size of the image formed by a convex lens when the object is placed at infinity.
    

    ANS:The image is on the opposite side of the object at focus; it is real, inverted and highly diminished(point sized).

    
    
38. Mention the position, nature and size of the image formed by a convex lens when the object is placed beyond 2F₁.
    

    ANS:The image is between F₂ and 2F₂; it is real, inverted and diminished.

    
    
39. Mention the position, nature and size of the image formed by a convex lens when the object is placed at 2F₁.
    

    ANS:The image is at 2F₂; it is real, inverted and of the same size as the object.

    
    
40. Mention the position, nature and size of the image formed by a convex lens when the object is between F₁ and 2F₁.
    

    ANS:The image is beyond 2F₂; it is real, inverted and enlarged.

    
    
41. Mention the position, nature and size of the image formed by a convex lens when the object is placed at focus F₁.
    

    ANS:The image is at infinite distance; it is real, inverted and highly enlarged.

    
    
42. Mention the position, nature and size of the image formed by a convex lens when the object is placed between focus F₁ and optical center O.
    

    ANS:The image is on the same side of the lens as the object; it is virtual, erect and enlarged.

    
    
43. Define: Power of lens.
    

    ANS:The reciprocal of the focal length(f) of a lens is called the power of that lens.

    
    
44. What is the SI unit of power of lens?
    

    ANS:The SI unit of power of lens is dioptre.

    
    
45. The power of a convex lens is positive.True or false?
    

    ANS:Yes, this is a true statement.

    
    
46. The power of a concave lens is positive.True or false?
    

    ANS:No, this is a false statement.

    
    
47. Which instrument is used to measure the power of a lens?
    

    ANS:Dioptremeter is used to measure the power of a lens.

    
    
48. What is the power of a convex lense whose focal length is 50 cm ?
    

    ANS:(+)2.0 D
    

    
    
49. The power of a lens is (-)4.0 D. What is its focal length in cm ?
    

    ANS:(-)25 cm, the negative sign indicates that the lens is concave.
    

    
    
50. On what does the lateral shift of an emergent ray depend in case of a rectangular glass slab ?
    

    ANS:The lateral shift is proportional to the perpendicular distance between two refracting surfaces of the glass slab.
    

    
    
51. Define: Critical angle.
    

    ANS:The angle of incidence of a ray for which the angle of refraction is 90° is called critical angle.

    
    
52. Define: Total internal reflection.
    

    ANS:When the angle of incidence of a ray is greater than the critical angle, the refracted ray is in the same medium, i.e. the light is totally reflected in the same medium. This is known as total internal reflection.

    
    
53. What happens to a ray of light travelling from optically rarer to optically denser medium?
    

    ANS:The ray of light bends towards the normal.

    
    
54. State Snell's law.
    

    ANS:The ratio of the sine of the angle of incidence to the sine of the angle of refraction is constant.

    
    
55. Which type of waves are light waves?
    

    ANS:Light waves are electromagnetic(non-mechanical)waves.

    
    
56. A medium is necessary for the propagation of light waves.True or false?
    

    ANS:No, this is a false statement.

    
    
57. If incident angle is 40° for a plane mirror, what should be the angle of reflection?
    

    ANS:The angle of reflection should be 40°.

    
    
58. What is the type of mirror having focal length +10 cm?
    

    ANS:The mirror is convex.

    
    
59. Which medium has higher refractive index, glass or water?
    

    ANS:Glass has higher refractive index.

    
    
60. In which medium is the velocity of light higher, glass or water?
    

    ANS:The velocity of light is higher in water.

    
    
61. Give the names of two phenomena occuring due to refraction.
    

    ANS:Twinkling of stars and mirage are the two phenomena occuring due to refraction.

    
    
62. If the focal length of convex lens is 25 cm, what is its power?
    

    ANS:The power of the given convex lens is 4.0 D or +4.0 D.(HINT: p = 1/f where f is in meter)

    
    
63. Which kind of lens has positive power, converging or diverging ?
    

    ANS:A converging lens has positive power.

    
    
64. Mention the unit of refractive index.
    

    ANS:Refractive index is unitless.

    
    
65. Which type of mirror is used as rear-view mirror in vehicles ?
    

    ANS:A convex mirror is used as rear-view mirror in vehicles.

    
    
66. The refractive index of diamond is 2.42. What is the meaning of this statement in relation to the speed of the light ?
    

    ANS:It means that the light travels 2.42 times faster in vacuum than in diamond.

    
    

INTRODUCTION TO NANOTECHNOLOGY-III : LONG ANSWERS

GIVE ANSWER IN DETAIL

*INDEX-TOPIC SEARCH

1. EXPLAIN WITH DIAGRAM THE CONCEPT OF CARBON NANOTUBE.
   

   ANS:Richard Smalley conceptualised bucky balls, big enough to make tubes. It was made possible by bonding the bucky balls together in a row and truncating the overlapping regions of bucky balls.
   
   
   
   
   
   Nanotubes are cylinders in the form of lattice of carbon atoms.Each carbon atom is covalently bonded to three other carbon atoms. Hence carbon nanotubes are basically a chain of bucky balls whose ends never close into a sphere when they are formed and a lattice of atoms in the shape of a cylinder is formed.
   
   
   
   
   Nanotubes can be Single-Walled Nano Tube(SWNT) or Multi-Walled Nano Tube(MWNT).SWNT consists of a single cylinder whereas MWNT consists of multiple concentric nanotubes of different diameters.
   

   
   
2. DISCUSS THE CHARACTERISTICS AND PROPERTIES OF CARBON NANOTUBES.
   

   ANS:The characteristics and properties of carbon nanotubes are:
   

   1. Tensile Strength:
      
      • The tensile strength of a carbon nanotube is about 100 times more than that of steel.
        
      • High tensile strength is due to the carbon-carbon bonds and the fact that each carbon nanotube is one large molecule.
        
      • Carbon nanotubes are elastic despite their high tensile strength.Therefore they can be bent like a rubber tube.
      
      
   2. Thermal Conductivity:
      
      • The thermal conductivity of carbon nanotubes is 10 times that of silver.
        
      • Carbon nanotubes conduct heat by vibrations of the covalent bonds between the carbon atoms. The atoms wiggle around themselves and transmit heat through the material.
        
      • Because the bonds in the molecule are elastic like spring the vibrations occur.
        
      • These vibrations transmit quickly through the tube due to the stiffness of the tube.
      
      

   
   

   
   
3. WHAT IMPROVEMENT WILL NANOTECHNOLOGY BRING ABOUT? EXPLAIN.
   

   ANS:The nanotechnology is expected to bring about the following improvement in near future:
   

   • Global Positioning System(GPS) will be more accurate, smaller and cost-effective.
     
   • Computers will be smaller and faster.
     
   • Super-hard materials with tunable melting points will be made.
     
   • Cell-phone batteries will have longer life.
     
   • DNA fingerprinting will become quicker and more accurate.
     
   • Medical diagnosis and delivery systems will be more efficient.
     
   • Active nanoingredients in sunscreen creams will bring quick skin health.
     
   • Information routing will be done at the speed of light.

   
   

   
   
4. DESCRIBE THE IMPORTANCE OF CARBON IN NANOTECHNOLOGY.
   

   ANS:The importance of carbon in nanotechnology is as follows:
   

   • Carbon is found in great abundance in natural materials.
     
   • Materials containing carbon exhibit a wide range of properties due to specific reasons.
     
   • A carbon atom can form covalent bonds with different types of atoms.
     
   • A carbon atom can form covalent bonds with four other atoms at a time resulting in long-chained molecules.
     
   • A carbon atom can bond strongly to other carbon atoms in many different ways forming a variety of structures.
     
   • All this makes carbon an important element in nanotechnology where the basic structure is a Bucky Ball which is a molecule of 60 carbon atoms forming a sphere-like structure.
     
   • A series of such spheres (Bucky Balls) connected to one another without the ends closing form carbon nanotubes which have many applications in nanotechnology.
     
   • All this makes carbon a very important element for nanotechnology.

   
   
5. EXPLAIN HOW NANOTECHNOLOGY PLAYS AN IMPORTANT ROLE IN SECURITY.
   

   ANS:Nanotechnology plays an important role in security in the following way:
   

   • Superior and Lightweight Material:Nanomaterials ten times stronger than steel will revolutionise battle tanks, spacecrafts, skyscrappers and bridges. We can tune the melting points of nanomaterials by controlling their particle size in the range of nanoscale.
     
   • Powerful Munitions:New nanometals and nanosize particles such as nanoaluminium are chemically more reactive. Varying the size of these particles in munitions will cause minimum collateral damage during explosion.
     
   • Advanced Computing:More powerful and small computers will encrypt date and provide round-the-clock security,e.g. Quantum Cryptography.
     
   • Powerful Chemical Sensors:We can develop highly sensitive chemical sensors which can accurately pinpoint a single molecule out of billion molecules floating around.These sensors will be cheaper and disposible.
     
   
   

   
   

   
   
6. WRITE A NOTE ON NANOTECHNOLOGY AND HEALTHCARE.
   

   ANS:Nanotechnology has wide scope of application in the field of healthcare.
   

   • Diagnostics:
     
     1. Better,cheaper and quicker diagnostic equipment will enable instant diagnosis and drug application.
        
     2. For example:Floating contrast agents into bloodstream will allow detection of diseases with accuracy and speed.
        
     3. Quick mapping of DNA for newly-born babies will give information of potential problems likely to occur in future.This will enable us to curtail diseases at the early stage of life.
     
     
     
     
   • Novel Drugs:Nanotechnology can make drug delivery in precise amount and to precise site in our body.For example: A nanoshell of 100 nm diameter will float through the body, attaching only to cancerous cells.Upon excitation by a laser beam those nanoshells will dissipate heat and the tumour will get destroyed.
     
   
   

   
   

   
   
7. MENTION SOME BENEFITS OF NANOTECHNOLOGY TO MANKIND.
   

   ANS:Some benefits of nanotechnology to mankind are:
   

   • Nanoparticle medicines with vastly improved delivery and control.
     
   • Highly improved printing by nanoscale particles with best properties of both dyes and pigments.
     
   • Vastly improved lasers and magnetic disc heads made by controlling layer thickness.
     
   • 'Nanofood' molecularly identical to the organic food.
     
   • Better, cheaper and quicker diagnostic equipment to enable instant diagnosis and drug application.
     
   • Drug delivery in precise amount to precise site in our body for the treatment of fatal diseases like cancer.
     
   • Better,efficient and cheaper means of security with the help of superior and lightweight materials, powerful munitions, advanced computing and powerful chemical sensors.
     
   • Transformation of electricity into light with the help of nanocrystals preventing excessive loss of energy due to heating.
     
   • Inexpensive and more efficient solar cells and hydrogen fuel cells.
     
   • Lighter, stronger and more efficient engine blocks for cars to save fuel.
     
   • Efficient water purification technology and thus access to clean water in third world countries.
     
   
   

   
   

   
   

INTRODUCTION TO NANOTECHNOLOGY-II : BRIEF ANSWERS

ANSWER IN BRIEF

*INDEX-TOPIC SEARCH

1. DEFINE: NANOSCIENCE AND NANOTECHNOLOGY IN THE MODERN CONTEXT.
   

   ANS:Nanoscience is the study of fundamental principles of molecules and other systems whose at least one of the dimensions lies between 1 nm and 100 nm range.
   
   Nanotechnology is the tool to harness the knowledge of nanoscience for creating new useful materials, devices, machines and systems with novel properties due to their small size. Nanotechnology is building structures, atom-by-atom or molecule-by-molecule, that will be helpful in manufacturing devices and systems.
   
   Nanoscience and nanotechnology will find the ways to make stronger materials,detect diseases in blood-stream, build tiny machines, generate light and enormous energy and purify water with the help of nanosize particles.
   

   
   
2. WHY IS NANOTECHNOLOGY A GENERAL-PURPOSE TECHNOLOGY ?
   

   ANS:Nanotechnology is a general purpose technology because in its mature form it will have significant impact on almost all industries and all areas of society. It offers better built, longer lasting, cleaner, safer and smarter products useful in domestic purposes, communication, medicines, transportation, agriculture and industry.
   

   
   
3. WHY IS CARBON A FUNDAMENTAL ELEMENT IN NANOTECHNOLOGY? EXPLAIN.
   

   ANS:Carbon is a fundamental element in nanotechnology due to the following properties.
   

   1. A carbon atom can bond with many different types of atoms by forming covalent bonds.
      
   2. Each carbon atom can form such covalent bonds with four other atoms at a time and thus form long chains of atoms.
      
   3. No other element except carbon can bond strongly to other carbon atoms in many different ways.
      

   
   

   
   


4. EXPLAIN HOW NANOTECHNOLOGY IS USED IN DIAGNOSTICS.
   

   ANS:Nanotechnology is useful in diagnostics in the following way:
   

   1. Better, cheaper and quicker diagnostic equipment will enable instant diagnosis and drug application.
      
   2. For example, floating contrast agents into bloodstream will allow detection of disease with accuracy and speed.
      
   3. Quick mapping of DNA for newly born babies will give information of potential problems likely to occur in future.This will enable us to curtail diseases at early stage of life.
      

   
   

   
   


5. WHICH FIELDS OF TECHNOLOGY WILL BE IMPORTANT IN FUTURE? or MENTION SOME IMPORTANT FUTURE TECHNOLOGIES THAT WILL BE IN FOREFRONT DURING 21ST CENTURY.
   

   ANS:The fields of technology that will be important in future are:
   

   1. Nanotechnology
      
   2. Biotechnology
      
   3. Information Technology
      
   4. X-Rays
      
   5. Teleportation
      
   6. LASERS
      
   7. Robotics
      

   
   



6. WHAT POSSIBILITIES WILL NANOTECHNOLOGY OFFER ?
   

   ANS:Nanotechnology will offer following possibilities such as :
   

   
   
   1. Cellular repair
   2. Artificial intelligence
   3. Inexpensive space travel
   4. Clean and abundant energy.
   5. Environmental restoration.
      

   
   

   
   
7. EXPLAIN THE INFLUENCE OF NANOTECHNOLOGY ON ENVIRONMENT.
   

   ANS:Nanotechnology will have great influence on environment.
   

   1. It would help repair past environmental damages and thus reform the environment.
      
   2. It can solve present environmental problems.
      
   3. It would prevent future environmental impacts.
      
   4. It would sustain the planet Earth for future generations.
      

   
   



8. DESCRIBE THE STRUCTURE AND CONFIGURATION OF A BUCKY BALL.
   

   ANS:
   
   
   A bucky ball is a molecule of 60 carbon atoms(C₆₀) in the architectural configuration of a soccer ball(sphere).Each carbon atom is bound to three adjacent carbon atoms forming a sphere of around 1.0 nm diameter.The bonds between atoms form a pattern of joined hexagons and pentagons similar to the panels on a soccer ball.
   



9. GIVE THE APPLICATIONS OF BUCKY BALLS AND CARBON NANOTUBES.
   

   ANS:The applications of bucky balls and carbon nanotubes(i.e.,nanotechnology) are:
   

   1. In electronics
   2. In food and agriculture
   3. In sports and toys
      
   4. In spintronics
   5. In photonics
   6. In display panels
   7. In space vehicles
      
   8. In the field of energy
   9. In medicine and diagnosis
   10. In consumer goods
       

   
   



10. "NANOTECHNOLOGY PLAYS BY DIFFERENT RULES." EXPLAIN THE STATEMENT.
    

    ANS:How matter behaves at nanoscale is the main aspect of nanotechnological research. The rules that govern large systems may not work at this scale. This is because nanomaterials have larger surface area-to-volume ratio.Therefore, phenomena like sticking and friction have much more dominance and importance at nanoscales as compared to large dimensions.Thus nanotechnology plays by different rules.
    



11. MENTION THE USE OF NANOTECHNOLOGY FOR RESOURCES LIKE ENERGY AND WATER.
    

    ANS:

    
    
    1. ENERGY : Nanocrystals will transform electricity into light without loss of energy due to heating. Solar cells and hydrogen fuel cells will become inexpensive and efficient. Cars will become more efficient as lighter and stronger engine blocks will save fuel.
       
    2. WATER :Efficient water purification with the help of nanotechnology will allow third-world countries to have access to clean water.
       

    
    

    
    
12. WHAT CAN WE EXPECT TO BE IMPROVED IN NEAR FUTURE DUE TO NANOTECHNOLOGY ?
    

    ANS:

    
    
    • Smaller and cost-effective accurate Global Positioning System(GPS)
    • Faster and smaller computers
    • Super hard materials with tunable melting temperatures
    • Cell phones with longer battery life
    • Quick and accurate DNA finger-printing
    • New and efficient medical diagnosis and delivery systems
    • Quick skin healing by sun screen creams having active nano-ingredients
    • Information routing at the speed of light.
      

    
    

    
    
13. WHAT CAN WE DO WITH THE HELP OF STUDY OF NANOSIZE PARTICLES, DEVICES AND COMPOSITES ?
    

    ANS:With the help of the study of nanosize particles, devices and composites we can develop stronger materials, detect diseases in blood streams, build tiny machines, generate light and enormous energy and purify water.
    

    
    
14. WRITE A NOTE ABOUT AFM AND STM.
    

    ANS: AFM(Atomic Force Microscope) and STM(Scanning Tunelling Microscope) are instruments used to see objects of size smaller than 10000 nm since the human eye has the limitation that it cannot see objects smaller than 10000 nm.
    Gern Binnig and Heinrich Rohre of IBM Research Lab invented STM in 1981.
    With the help of such instruments(machines) we can study atoms and manipulate them to develop new nanostructures.
    

    
    

INTRODUCTION TO NANOTECHNOLOGY-I : MCQs & SHORT ANSWERS

*INDEX-TOPIC SEARCH

MULTIPLE-CHOICE QUESTIONS

SELECT THE CORRECT ALTERNATIVE:

1. "There is a plenty of room at the bottom." This was stated by
   
   
   
   1. Issac Newton
      
   2. Albert Einstein
      
   3. Richard Feynman
      
   4. Eric Drexler
      
   
   
2. 1 nanometre= _______ cm.
   
   
   
   1. 10^(-9)
      
   2. 10^(-8)
      
   3. 10^(-7)
      
   4. 10^(-6)
      
   
   
3. The size of E.coli bacteria is ______ nm
   
   
   
   1. 75000
      
   2. 2000
      
   3. 200
      
   4. 5
      
   
   
4. The diameter of human hair is _______ m
   
   
   
   1. 75000
      
   2. 75
      
   3. 7.5 x 10^(-5)
      
   4. 7.5 x 10^(-9)
      
   
   
5. The most important property of nanomaterials is
   
   
   
   1. force
      
   2. friction
      
   3. pressure
      
   4. temperature
      
   
   
6. The diameter of a bucky ball is about ______
   
   
   
   1. 1 A^o
      
   2. 100 A^o
      
   3. 1 nm
      
   4. 10 nm
      
   
   
7. A bucky ball is a molecule consisting of ___ carbon atoms
   
   
   
   1. 50
      
   2. 60
      
   3. 75
      
   4. 100
      
   
   
8. The cut-off limit of human eye to see is _____ nm
   
   
   
   1. 10
      
   2. 100
      
   3. 1000
      
   4. 10000
      
   
   
9. 1 meter = ______ nm.
   
   
   
   1. 10⁹
      
   2. 10^(-9)
      
   3. 10¹⁰
      
   4. 10^(-10)
      
   
   
10. The diameter of a bucky ball is about ______
    
    
    
    1. 1 A^o
       
    2. 10 A^o
       
    3. 100 A^o
       
    4. 1000 A^o
       
    
    
11. The diameter of hydrogen atom is ______ nm.
    
    
    
    1. 10
       
    2. 1
       
    3. 0.1
       
    4. 0.01
       
    
    
12. The size of a quantum dot is ______ m.
    
    
    
    1. 5
       
    2. 5 x 10^(-9)
       
    3. 5 x 10^(-10)
       
    4. 5 x 10^(-11)
       
    
    
13. 20 micron = ______ nm
    
    
    
    1. 20 x 10^(-9)
       
    2. 20 x 10⁹
       
    3. 200
       
    4. 20000
       
    
    
14. 1 mm = ______ nm
    
    
    
    1. 10⁶
       
    2. 10^(-6)
       
    3. 10⁷
       
    4. 10^(-7)
       
    
    
15. The hardest material found in nature is ______.
    
    
    
    1. steel
       
    2. topaz
       
    3. diamond
       
    4. quartz
       
    
    
16. ______ are the extentions of bucky balls.
    
    
    
    1. Geodesic domes
       
    2. Hexagons
       
    3. Carbon nanotubes
       
    4. AFM and STM
       
    
    
17. Nanotechnology, in other words, is
    
    
    
    1. Carbon engineering
       
    2. Atomic engineering
       
    3. Small technology
       
    4. Microphysics
       
    
    
18. The width of carbon nanotube is ______nm.
    
    
    
    1. 1
    2. 1.3
    3. 1.55
    4. 10
       
    
    
19. The diameter of fly ash particles is _____ μm
    
    
    
    1. 5-10
    2. 10-20
    3. 20-30
    4. 100
       
    
    
20. The tensile strength of a carbon nanotube is _____ times that of steel.
    
    
    
    1. 10
    2. 25
    3. 100
    4. 1000
       
    
    
21. The ratio of thermal conductivity of silver to that of a carbon nanotube is _____.
    
    
    
    1. 100 : 1
    2. 1 : 100
    3. 10 : 1
    4. 1 : 10
       
    
    
22. In a bucky ball, each carbon atom is bound to _____ adjacent carbon atoms.
    
    
    
    1. 1
    2. 2
    3. 3
    4. 4
       
    
    
23. The size of red and white blood cells is in the range of _____μm.
    
    
    
    1. 2-5
    2. 5-7
    3. 7-10
    4. 10-15
       
    
    

ANSWERS TO MCQs:

(1) C (2) C (3) B (4) C (5) B (6) C (7) C (8) D (9) A (10) B (11) C (12) B (13) D (14) A (15) C (16) C (17) B (18) B (19) B (20) C (21) D (22) C (23) A

SHORT ANSWERS

1. Who coined the word "Nanotechnology"?
   

   ANS: K. Eric Drexler coined the word "Nanotechnology".

   
   
2. Who wrote the book "Engines of Creation"?
   

   ANS: K. Eric Drexler wrote the book "Engines of Creation".

   
   
3. What is the meaning of the Greek word "Nano"?
   

   ANS: "Nano" means "dwarf".

   
   
4. What is the meaning of "Technology"?
   

   ANS:"Technology" is a process of using scientific principles and techniques to design new materials, devices, and systems for prosperity, comforts, betterment and enhancement of human life.

   
   
5. What is Atomic Engineering?
   

   ANS:Atomic Engineering is the science involving manufacture of products with different properties by rearrangement of atoms.

   
   
6. Define: Nanotechnology.
   

   ANS:Nanotechnology is atom-by-atom or molecule-by-molecule building of structures that will be helpful in manufacturing new devices and systems.
   

   
   
7. How much is 1 micron in meter ?
   

   ANS:1 micron is equal to 10^-6 meter.
   

   
   
8. What is the size of an integrated circuit transistor?
   

   ANS:The size of an integrated circuit transistor is 90 nm.

   
   
9. What is the size of a virus?
   

   ANS:A virus is 50 nm in size.

   
   
10. Mention the width of a DNA molecule.
    

    ANS:A DNA molecule has width of about 2 nm.

    
    
11. What is the diameter of the hydrogen atom?
    

    ANS:The diameter of the hydrogen atom is 0.1 nm.

    
    
12. What is the full form of MEMS?
    

    ANS:"MicroElectro Mechanical Systems" is the full form of MEMS

    
    
13. What is the size of red blood cells?
    

    ANS:The size of red blood cells is 5000 nm.

    
    
14. What is the size of a quantum dot?
    

    ANS:The size of a quantum dot is 5 nm.

    
    
15. Who invented STM(Scanning Tunneling Microscope)?
    

    ANS:Gern Binnig and Heinrich Rohre of IBM Research Lab invented STM in 1981.

    
    
16. What can be considered as a loose atom or molecule floating in space?
    

    ANS:Anything smaller than a nanometer can be considered as a loose atom or molecule floating in space.

    
    
17. What made it possible to study atoms and their manipulation in developing new structures ?
    

    ANS:The invention of Scanning Tunneling Microscope(STM) made it possible to study atoms and their manipulation in developing new structures.
    

    
    
18. What is the full form of AFM?
    

    ANS:The full form of AFM is Atomic Force Microscope.

    
    
19. Which two types of fundamental molecules find wide applications in nanotechnology?
    

    ANS:Bucky balls and carbon nanotubes are two types of fundamental molecules that find wide applications in nanotechnology.

    
    
20. Why does nanotechnology play by different rules ?
    

    ANS:Nanotechnology plays by different rules because of larger surface area relative to the volume of nanomaterials.
    

    
    
21. Who discovered Buckminsterfullerene(bucky ball)?
    

    ANS:Robert F. Curl,Jr.; Harold W. Croto; and Richard E. Smalley discovered the buckminsterfullerene in 1985.

    
    
22. What does a bucky ball comprise of?
    

    ANS:A bucky ball comprises of 60 carbon atoms in the architectural configuration of a soccer ball(sphere).

    
    
23. Who designed the famous geodesic dome?
    

    ANS:American architect Buckminster Fuller designed the famous geodesic dome.

    
    
24. What are carbon nanotubes? OR What are fullerenes?
    

    ANS:Carbon nanotubes are long tubular structures formed by joining bucky balls without their ends closing so that spheres are not formed.

    
    
25. Who conceptualised carbon nanotubes?
    

    ANS:Richard Smalley conceptualised carbon nanotubes.

    
    
26. What is a bucky tube?
    

    ANS:A bucky tube is a carbon nanotube derived from bucky balls.

    
    
27. Mention the types of carbon nanotubes.
    

    ANS:The types of carbon nanotubes are:(1) Single Walled Nano Tube (SWNT)and (2)Multi Walled Nano Tube (MWNT)

    
    
28. List out the areas of nanoscience.
    

    ANS:The areas of nanoscience are:(1)nanotubes (2)nanofabrication (3)nanomaterials (4)nanocomposites

    
    
29. Who photographed nanotubes for the first time ?
    

    ANS:Sumio Tijima of NEC Laboratory photographed nanotubes for the first time.
    

    
    
30. Why do carbon nanotubes have very high tensile strength ?
    

    ANS:Carbon nanotubes have very high tensile strength due to carbon-carbon bonds and the fact that each carbon tube is a very large molecule.
    

    
    
31. How do carbon nanotubes conduct heat ? OR Why do carbon nanotubes have high thermal conductivity ?
    

    ANS:Carbon nanotubes have high thermal conductivity because they conduct heat by vibrations of covalent bonds between carbon atoms.
    

    
    
32. How is nanotechnology useful in destroying tumours of cancer ?
    

    ANS:A nanoshell of 100nm diameter floating through the body will be able to get attached only to cancerous cells which upon excitation by a laser beam will dissipate heat and destroy the tumour.
    

    
    
33. How can the melting point of materials be tuned using nanotechnology ?
    

    ANS:The melting point of materials can be tuned by controlling their particle size in the range of nanoscale.
    

    
    
34. How can collateral damage be minimized during explosion using nanotechnology ?
    

    ANS: The collateral damage during explosion can be minimized by varying the size of nanoparticles in munitions.
    

    
    
35. What is the use of nanocrystals ?
    

    ANS:Nanocrystals can be used to transform electricity into light without excessive loss of energy due to heating.
    

    
    
36. Which fields of science will be affected by the progress of nanotechnology ?
    

    ANS:The fields like nanotubes, nanofabrication, nanomaterials and nanocomposites will be affected by the progress of nanotechnology.
    

    
    
37. Mention two phenomena which are dominant and important at nanoscales(as compared to larger dimensions).
    

    ANS:Sticking and friction are dominant and important at nanoscales.
    

    
    
38. How can the mapping of DNA of a newly born baby be useful ?
    

    ANS:The mapping of DNA of a newly born baby can help obtain information about future potential problems, enabling to curtail diseases at an early stage.
    

    
    
39. Mention the range of wavelength of visible light in nanometer.
    

    ANS: The range of wavelength of visible light is 400 to 700 nm.
    

    
    
40. Who outlined the "Vision and Prospects of Atomic Engineering'?
    

    ANS: Richard Feynman.
    

    
    
41. What is the diameter of human hair?
    

    ANS: The diameter of human hair is 75000 nm.
    

    
    
42. What is the full form of GPS?
    

    ANS: The full form of GPS is Global Positioning System.
    

    
    
43. What is the size of MEMS?
    

    ANS: The size of MEMS is 10^-6 to 10 ^-4 m.
    

    
    
44. What is the size of a nanoshell?
    

    ANS: The size of a nanoshell is 100 nm.
    

    
    

WELCOME TO MY SCIENCE BLOG

This is my special blog meant only for my students.I will be posting topics of SCIENCE for Highschool students of Class 10 of Gujarat Secondary Education Board (GSEB) but I hope that this will be useful to all the students of Class 10 of different Boards of Education in India.

WELCOME TO MY ANSWER TO YOUR PROBLEMS !!!

**INDEX**SEARCH TOPIC HERE**

*Nanotechnology(MCQs & Short Ans)

*Nanotechnology(Brief Answers)

*Nanotechnology(Long Answers)

*LIGHT(MCQs & Short ANS)

*LIGHT(Brief Answers)

*LIGHT(Long Answers)

*LIGHT(Numericals)

*DISPERSION OF LIGHT(MCQs & Short ANS)

*DISPERSION OF LIGHT(Brief Answers)

*DISPERSION OF LIGHT(Long Answers)

*ELECTRICITY(MCQs & Short ANS)

*ELECTRICITY(Brief Answers)

*ELECTRICITY(Long Answers)

*ELECTRICITY(Numericals)

*MAGNETIC EFFECTS OF ELE. CURRENT(MCQs & Short ANS)

*MAGNETIC EFFECTS OF ELE. CURRENT(Brief Answers)

*MAGNETIC EFFECTS OF ELE. CURRENT(Long Answers)

*ENERGY SOURCES(MCQs & Short ANS)

*ENERGY SOURCES(Brief Answers)

*ENERGY SOURCES(Long Answers)

*UNIVERSE(MCQs & Short ANS)

*UNIVERSE(Brief Answers)

*UNIVERSE(Long Answers)

*RATE OF REACTION-CHEMICAL EQUILIBRIUM-MCQs SHORT ANSWERS

*RATE OF REACTION-CHEMICAL EQUILIBRIUM-BRIEF ANSWERS

*RATE OF REACTION-CHEMICAL EQUILIBRIUM-LONG ANSWERS

*RATE OF REACTION-CHEMICAL EQUILIBRIUM-NUMERICALS

*SOME IMPORTANT CHEMICAL COMPOUNDS-MCQs & SHORT ANSWERS

*SOME IMPORTANT CHEMICAL COMPOUNDS-BRIEF ANSWERS

*SOME IMPORTANT CHEMICAL COMPOUNDS-LONG ANSWERS

*METALS-MCQs & SHORT ANSWERS

*METALS-BRIEF ANSWERS

*METALS-LONG ANSWERS

*NONMETALS-MCQs & SHORT ANSWERS

*NONMETALS-BRIEF ANSWERS

*NONMETALS-LONG ANSWERS

*ORGANIC COMPOUNDS-MCQs & SHORT ANSWERS

*ORGANIC COMPOUNDS-BRIEF ANSWERS

*ORGANIC COMPOUNDS-LONG ANSWERS

*NUTRITION AND RESPIRATION IN ORGANISMS-MCQs & SHORT ANSWERS

*NUTRITION AND RESPIRATION IN ORGANISMS-BRIEF ANSWERS

*NUTRITION AND RESPIRATION IN ORGANISMS-LONG ANSWERS

*TRANSPORTATION-CIRCULATION-EXCRETION IN LIVING ORGANISMS-MCQs & SHORT ANSWERS

*TRANSPORTATION-CIRCULATION-EXCRETION IN LIVING ORGANISMS-BRIEF ANSWERS

*TRANSPORTATION-CIRCULATION-EXCRETION IN LIVING ORGANISMS-LONG ANSWERS

*CONTROL AND COORDINATION IN ORGANISMS-MCQs & SHORT ANSWERS

*CONTROL AND COORDINATION IN ORGANISMS-BRIEF & LONG ANSWERS

*REPRODUCTION IN ORGANISMS-MCQs & SHORT ANSWERS

*REPRODUCTION IN ORGANISMS-BRIEF ANSWERS

*REPRODUCTION IN ORGANISMS-LONG ANSWERS

*HEREDITY AND EVOLUTION-MCQs & SHORT ANSWERS

*HEREDITY AND EVOLUTION-BRIEF ANSWERS

*HEREDITY AND EVOLUTION-LONG ANSWERS

*ENVIRONMENT AND ENVIRONMENTAL PROBLEMS-MCQs & SHORT ANSWERS

*ENVIRONMENT AND ENVIRONMENTAL PROBLEMS-BRIEF ANSWERS

*ENVIRONMENT AND ENVIRONMENTAL PROBLEMS-LONG ANSWERS