ENERGY SOURCES - I :MCQs & SHORT ANSWERS

*INDEX-TOPIC SEARCH

MULTIPLE-CHOICE QUESTIONS

SELECT THE CORRECT ALTERNATIVE:

1. _______ is not a fossil fuel.
   
   
   
   1. Coal
   2. Natural gas
   3. Petroleum
   4. Wind energy
   
   
   
   
2. The coal reservoirs are estimated to last for another _______ years.
   
   
   
   1. 50
   2. 100
   3. 250
   4. 500
   
   
   
   
3. ________ reaction is continuously going on in sun.
   
   
   
   1. Thermonuclear fusion
   2. Thermonuclear fission
   3. Thermostatic fusion
   4. Thermostatic fission
   
   
   
   
4. How much energy does sun release in the form of radiation ?
   
   
   
   1. 3.8 x 10²⁴ joule/second
   2. 3.8 x 10²⁶ joule/second
   3. 1.7 x 10¹⁷ joule/second
   4. 1.7 x 10²⁶ joule/second
   
   
   
   
5. How much energy from sun reaches to earth's surface ?
   
   
   
   1. 3.8 x 10²⁴ joule/second
   2. 3.8 x 10²⁶ joule/second
   3. 1.7 x 10¹⁷ joule/second
   4. 1.7 x 10²⁶ joule/second
   
   
   
   
6. The average distance between the sun and the earth is _______.
   
   
   
   1. 1.5 x 10⁵ km
   2. 1.5 x 10⁶ km
   3. 1.5 x 10⁷ km
   4. 1.5 x 10⁸ km
   
   
   
   
7. The value of solar constant is ________.
   
   
   
   1. 1.335 kW/m²
   2. 1.533 kW/m²
   3. 1.358 kW/m²
   4. 1.353 kW/m²
   
   
   
   
8. Approximately ______ of energy striking the outer atmosphere of earth reaches its surface.
   
   
   
   1. 46 %
   2. 47 %
   3. 48 %
   4. 49%
   
   
   
   
9. Of the visible light ______ has the maximum wavelength and ______ has the minimum wavelength.
   
   
   
   1. red, green
   2. red, yellow
   3. red, violet
   4. violet, red
   
   
   
   
10. The wavelength of visible light is ________.
    
    
    
    1. 4 x 10^-7 to 8 x 10^-7 m
    2. 4 x 10^-6 to 8 x 10^-6 m
    3. 4 x 10⁷ to 8 x 10⁷ m
    4. 4 x 10⁶ to 8 x 10⁶ m
    
    
    
    
11. The wavelength of infrared rays is ______.
    
    
    
    1. less than that of red rays
    2. less than that of violet rays
    3. more than that of red rays
    4. more than violet but less than that of red rays
    
    
    
    
12. The wavelength of ______ is less than that of violet rays.
    
    
    
    1. ultraviolet rays
    2. red rays
    3. infrared rays
    4. green rays
    
    
    
    
13. Who used solar energy to run engines using hot air ?
    
    
    
    1. Ericson
    2. Gunter
    3. Thomson
    4. Joule
    
    
    
    
14. We get ______ kW solar energy per square meter.
    
    
    
    1. 1.353
    2. 0.66
    3. 47
    4. 3.8 x 10²⁶
    
    
    
    
15. Solar furnace at Mount Louis in France attains the temperature as high as ______ ° C.
    
    
    
    1. 2000
    2. 2500
    3. 3000
    4. 3500
    
    
    
    
16. A solar cell made of thin selenium wafer converts ______ % solar energy into electrical energy.
    
    
    
    1. 0.4
    2. 0.55
    3. 0.7
    4. 1.2
    
    
    
    
17. A thin wafer of ______ converts solar radiation in to electricity.
    
    
    
    1. sodium
    2. strontium
    3. stibium
    4. selenium
    
    
    
    
18. ______ is a semi-metal.
    
    
    
    1. Lead
    2. Carbon
    3. Silicon
    4. Mercury
    
    
    
    
19. ______ is used to make a solar cell.
    
    
    
    1. Silicon
    2. Graphite
    3. Mercury
    4. Platinum
    
    
    
    
20. What is used generally as connecting material in solar panels.
    
    
    
    1. Silicon
    2. Silver
    3. Selenium
    4. Germanium
    
    
    
    
21. Windmill was invented by _______about 250 years ago.
    
    
    
    1. the Chinese
    2. the Indians
    3. the Persians
    4. the Greek
    
    
    
    
22. How much electricity does the largest windfarm at Kanyakumari generate ?
    
    
    
    1. 200 MW
    2. 300 MW
    3. 400 Mw
    4. 500 MW
    
    
    
    
23. The Hydroelectric power-station on river Tapi in Gujarat is ______.
    
    
    
    1. Ukai
    2. Dhuvaran
    3. Panam
    4. Kadana
    
    
    
    
24. A high tide occurs ______.
    
    
    
    1. on every new moon day
    2. on every full moon day
    3. both on new moon and full moon day
    4. any time
    
    
    
    
25. Which of the following is not a product obtained by decomposition of wood ?
    
    
    
    1. Coal tar
    2. Coal gas
    3. Charcoal
    4. Wood pulp
    
    
    
    
26. The calorific value of biogas is ______ kJ/g.
    
    
    
    1. 30 - 35
    2. 35 - 40
    3. 40 - 45
    4. 45 - 50
    
    
    
    
27. Peat coal consists about_______ % carbon.
    
    
    
    1. 27
    2. 30
    3. 80
    4. 96
    
    
    
    
28. ______ is the coal of best quality.
    
    
    
    1. Peat
    2. Lignite
    3. Bitumin
    4. Anthracite
    
    
    
    
29. The Greek word 'petro' means ______.
    
    
    
    1. oil
    2. rock
    3. black liquid
    4. fuel
    
    
    
    
30. Usually petroleum is formed under ______.
    
    
    
    1. igneous rocks
    2. sedimentary rocks
    3. metamorphic rocks
    4. any rock
    
    
    
    
31. _______ (in 1855 AD) proved that petroleum (crude oil) can be used as a substitute of coal.
    
    
    
    1. Professor Brown
    2. Professor Barwood
    3. Professor Byron
    4. Professor Benjamin
    
    
    
    
32. During the refining of petroleum, the fraction having highest boiling temperature ______.
    
    
    
    1. condenses first
    2. condenses last
    3. does not condense
    4. remains in gaseous form
    
    
    
    
33. The calorific value of petrol is ______ kJ/g.
    
    
    
    1. 45
    2. 46
    3. 47
    4. 48
    
    
    
    
34. The number of carbon atoms in hydrocarbon molecule of kerosene is ______.
    
    
    
    1. 5 - 8
    2. 8 - 11
    3. 10 - 14
    4. 12 - 16
    
    
    
    
35. What is the calorific value of kerosene ?
    
    
    
    1. 45 kJ/g
    2. 46 kJ/g
    3. 47 kJ/g
    4. 48 kJ/g
    
    
    
    
36. What is the calorific value of diesel ?
    
    
    
    1. 45 kJ/g
    2. 46 kJ/g
    3. 47 kJ/g
    4. 48 kJ/g
    
    
    
    
37. In Gujarat ______ powerstation uses natural gas to produce electricity.
    
    
    
    1. Ukai
    2. Dhuvaran
    3. Tarapur
    4. Sardar Sarovar
    
    
    
    
38. The calorific value of ethanol is ______ kJ/g.
    
    
    
    1. 25
    2. 30
    3. 33
    4. 35
    
    
    
    
39. The calorific value of a hydrocarbon is higher if its ______.
    
    
    
    1. hydrogen : carbon ratio is higher
    2. hydrogen : carbon ratio is lower
    3. hydrogen : carbon ratio is unity
    4. hydrogen content is zero
    
    
    
    
40. The specific heat of water is _______.
    
    
    
    1. 4.186 kJ/g° C
    2. 4.186 cal/g° C
    3. 4.186 J/g° C
    4. 4.186 J/kg° C
    
    
    
    
41. The formula to find the calorific value of wax is ______.
    
    
    
    1. m x s x t
    2. w x s x t
    3. m x s x t x w
    4. m x s x t /w
    
    
    
    
42. 1 eV = _______ joule.
    
    
    
    1. 1.6 x 10^-17
    2. 1.6 x 10^-18
    3. 1.6 x 10^-19
    4. 1.6 x 10^-20
    
    
    
    
43. According to the theory of relativity
    
    
    
    1. E = m²c
    2. E = mc²
    3. E² = mc
    4. m = E²c
    
    
    
    
44. ______ contribute to the mass of an atom.
    
    
    
    1. Protons only
    2. Neutrons only
    3. Protons and neutrons
    4. Protons and electrons
    
    
    
    
45. If A is the atomic mass, Z is the atomic number and N is the number of neutrons in an atom, then
    
    
    
    1. A = N + Z
    2. N = A + Z
    3. Z = A + N
    4. A + Z + N = 0
    
    
    
    
46. _________invented artificial radioactivity.
    
    
    
    1. Marie Curie
    2. Berkley
    3. Lord Rutherford
    4. Maxwell
    
    
    
    
47. When uranium is bombarded by a neutron it splits into _______.
    
    
    
    1. barium and lanthanum
    2. barium and krypton
    3. lanthanum and boron
    4. boron and krypton
    
    
    
    
48. When uranium is bombarded by a neutron an element emitting _______ is produced.
    
    
    
    1. α-particles
    2. β-particles
    3. γ-rays
    4. x-rays
    
    
    
    
49. According to the Einstein's equation, E = mc², 1 u of mass is converted into _______ MeV of energy.
    
    
    
    1. 901
    2. 911
    3. 921
    4. 931
    
    
    
    
50. The energy produced by the fission of 1 kg of₉₂ U²³⁵ is equivalent to that produced by ______ tons of coal.
    
    
    
    1. 1000
    2. 1500
    3. 2000
    4. 2500
    
    
    
    
51. How many neutrons are released at the end of each splitting of an atom ?
    
    
    
    1. 2 - 3
    2. 3 - 4
    3. 4 - 5
    4. 1 - 2
    
    
    
    
52. What is the required temperature to expedite thermonuclear fusion reaction ?
    
    
    
    1. 10⁶ K
    2. 10⁸ K
    3. 10⁹ K
    4. 10¹⁰ K
    
    
    
    
53. The energy of a neutron released during a fission process should be reduced by about ______ part to convert it into a thermal neutron.
    
    
    
    1. 10²
    2. 10⁵
    3. 10⁸
    4. 10^-5
    
    
    
    
54. Which one of the following is not a naturally occuring isotope of uranium ?
    
    
    
    1. U²³⁸
    2. U²³⁶
    3. U²³⁵
    4. U²³⁴
    
    
    
    
55. In India, about ______ % of total power is generated by using nuclear energy.
    
    
    
    1. 3
    2. 5
    3. 7
    4. 9
    
    
    
    
56. How much energy is produced when two₁H² nuclei fuse to produce ₁H³ and ₁H¹
    
    
    
    1. 1.0 MeV
    2. 3.3 MeV
    3. 4.0 MeV
    4. 1000 MeV
    
    
    
    
57. _______ gm of deuterium is obtained from 1 cubic meter of seawater.
    
    
    
    1. 30
    2. 33
    3. 36
    4. 40
    
    
    
    
58. 1 gallon of deuterrium releases energy equivalent to that released by ______ gallons of petrol after combustion.
    
    
    
    1. 600
    2. 800
    3. 1000
    4. 1200
    
    
    
    
59. Bombardment of neutron on ₃Li⁶ gives _______.
    
    
    
    1. ₀H¹
    2. ₁H¹
    3. ₁H²
    4. ₁H³
    
    
    
    
60. ₁H³ + ₁H² ----> ₂He⁴ + ₀n¹ + _______ MeV.
    
    
    
    1. 16.7
    2. 17.6
    3. 3.3
    4. 4.0
    
    
    
    
61. The radioactive radiations of Chernobyl blast were _______ times the radiation spread during the Hiroshima blast.
    
    
    
    1. 20
    2. 50
    3. 100
    4. 200
    
    
    
    
62. Which of the following is not associated with solar energy ?
    
    
    
    1. Fossil fuel
    2. Hydel energy
    3. Geothermal energy
    4. Wind energy
    
    
    
    
63. How much temperature can be obtained in the solar furnace installed at Mount Louis in France ?
    
    
    
    1. 2000° C
    2. 3000° C
    3. 3500° C
    4. 4000° C
    
    
    
    
64. Which of the following is an optional form of energy ?
    
    
    
    1. Geothermal energy
    2. Natural gas
    3. Petroleum
    4. Hydrogen
    
    
    
    
65. By which process is solar energy converted into chemical energy ?
    
    
    
    1. Evaporation
    2. Greenhouse effect
    3. Photosynthesis
    4. None of the three
    
    
    
    
66. Who was the first scientist to prepare isotopes artificially ?
    
    
    
    1. Fermi
    2. Hann
    3. Rutherford
    4. Strassmann
    
    
    
    
67. 
    
    
    
    
    
    
    

ANSWERS


(1) D (2) C (3) A (4) B (5) C (6) D (7) D (8) B (9) C (10) A (11) C (12) A (13) A (14) B (15) C (16) C (17) D (18) C (19) A (20) B (21) C (22) B (23) A (24) B (25) D (26) B (27) A (28) D (29) B (30) B (31) D (32) A (33) C (34) C (35) D (36) A (37) B (38) B (39) A (40) C (41) D (42) C (43) B (44) C (45) A (46) C (47) B (48) B (49) D (50) D (51) A (52) A (53) C (54) B (55) A (56) C (57) B (58) A (59) D (60) B (61) D (62) B (63) B (64) A (65) C (66) C

SHORT QUESTIONS

ANSWER IN SHORT:

1. What is the primary source of energy ?
   
        ANS :Sun is the primary source of energy.


2. Mention the forms of energy of sun.
   
        ANS :Sun's energy mostly consists of light and heat in the form of solar energy, wind energy, bioenergy, etc.


3. Mention some conventional sources of energy.
   
        ANS :Wood, dung-cakes, coal, kerosene, LPG, petrol, CNG, diesel, electricity, etc. are some conventional sources of energy.


4. What is the full form of energy ?
   
        ANS :The full form of LPG is Liquefied Petroleum Gas.


5. What is the full form of CNG ?
   
        ANS :The full form of CNG is Compressed Natural Gas.


6. Mentiun some nonrenewable sources of energy.
   
        ANS :Petroleum, coal, natural gas, etc. are nonrenewable sources of energy.


7. Why are petroleum, coal, natural gas, etc. called nonrenewable sources of energy ?
   
        ANS :Petroleum, coal, natural gas, etc are called nonrenewable sources of energy because their formation takes millions of years and once utilized they cannot be reformed or regenerated in very short time.


8. Mention direct or indirect sources of Sun's energy. OR Mention the sources of energy having direct or indirect link to the Sun.
   
        ANS :Solar energy, hydel energy, wind energy, tidal energy, biogas, etc. are direct or indirect forms of sun's energy.


9. What do we mean by renewable sources of energy ?
   
        ANS :Those sources of energy which are expected to last for a very long period and which can be regenerated within very short period are called renewable sources of energy.


10. In which form does the radiation from sun reach the earth ?
    
         ANS :The radiation from sun reaches the earth in the form of heat and visible light.


11. What is solar constant ?
    
         ANS :The intensity of solar radiation incident on unit cross-sectional area of earth exposed perpendicularly to the rays of sun at an average distance is called solar constant. Its value is 1.353 kW/m².[NOTE : "average distance" means 'average distance between earth and sun].


12. What is the wavelength of visible light ?
    
         ANS :The wavelength of visible light is 4000 A° to 8000 A° or 4 x 10^-7 m to 8 x 10^-7 m.


13. Give two examples of electromagnetic waves having wavelength less than that of ultraviolet rays.
    
         ANS :X - rays and γ - rays are examples of electromagnetic waves having wavelength less than that of ultraviolet rays.


14. How much of the sunlight passing through the atmosphere consists of infrared rays ?
    
         ANS :About one-third of the sunlight passing through the atmosphere consists of infrared rays.


15. What is the property of infrared rays ?
    
         ANS :Infrared rays are invisible and they can heat the object kept in their path.


16. Mention some devices using solar energy.
    
         ANS :Solar cooker, solar water heater, solar water pump, photoelectric cell, photovoltaic cell, etc are some devices using solar energy.


17. Mention the two categories of devices using solar energy.
    
         ANS :The two categories of devices using solar energy are :(1) devices that convert solar energy into heat and (2) devices that convert solar energy into electricity.


18. How much temperature is developed in solar cooker in 2-3 hour's time ?
    
         ANS :Temperature of about 100 - 140 °C (approx) is developed in solar cooker in 2-3 hour's time.


19. Which country prepared solar cooker industrially for the first time ?
    
         ANS :India (in 1962 AD) prepares solar cooker industrially for the first time.


20. What is the principle of solar concentrators ?
    
         ANS :A solar concentrator works on the following principle : A parallel beam of light incident on a concave mirror is focussed on the principal axis after reflection.


21. What type of reflectors are used generally in solar concentrators ?
    
         ANS :Large spherical or parabolic reflectors are used generally in solar concentrators.


22. What is the temperature achieved in simple domestic solar concentrator (heater) ?
    
         ANS :Approximately 180 - 200 °C temperature is achieved in domestic solar heaters.


23. What is a solar tower ?
    
         ANS :A solar concentrator kept at a height of 50 - 70 m from the ground, consisting of small plane mirrors to generate electricity from solar radiation is called a solar tower.


24. How many small mirrors are there in the solar furnace at Mount Louis in France ?
    
         ANS :There are more than 3500 small mirrors in the solar furnace at Mount Louis in France.


25. What is a solar cell ?
    
         ANS :Solar cell is a device which converts solar energy into electrical energy.


26. Where is the electrical energy produced by solar cells stored conventionally ?
    
         ANS :Convwntionally, the electrical energy produced by solar cells is stored in storage batteries.


27. Which type of energy does wind possess ?
    
         ANS :Wind possesses kinetic energy.


28. What is the basis of deciding the parameters like the height and the number of blades of a windmill ? OR On what basis is the windmill designed ?
    
         ANS :Average wind velocity and local environmental (geographical) parameters are the basis of deciding the parameters like the height and the number of blades of a windmill.


29. Where are the wind energy farms located in Gujarat ?
    
         ANS :Wind energy farms are located at Lamba near Porbandar, at Okha, Mandvi and at Dhank in Gujarat.


30. Where is the largest wind-energy farm located in India ?
    
         ANS :The largest wind-energy farm in India is located near Kanyakumari in Tamilnadu.


31. What is the full form of OTEC ?
    
         ANS :The full form of OTEC is Ocean Thermal Energy Conversion.


32. What is the full form of SRPP ?
    
         ANS :The full form of SRPP is Solar Run Power Plant.


33. For what is the OTEC process used ?
    
         ANS :OTEC process is used to convert thermal energy into electrical energy using temperature difference of oceanic waters flowing at different depths.


34. What is the benefit of ocean thermal energy ?
    
         ANS :The benefit of ocean thermal energy is that this energy is available round the clock whereas solar energy is available only during the daytime.


35. What is a tide ?
    
         ANS :The everyday movement of water level along the sea-shore is called tide.


36. What is tidal energy ?
    
         ANS :Tidal energy is the energy generated by the rise and fall of oceanic tides.


37. Tidal energy is an indirect form of solar energy. True or false ?
    
         ANS :This is a true statement.


38. What is geothermal energy ?
    
         ANS :Geothermal energy is the energy obtained from the heat of hot dry rocks in the earth's crust, geysers, hot springs, etc.


39. What is magma ?
    
         ANS :Magma is hot semifluid formed due to melting of rocks by interior heat of the earth.


40. What are hot spots ?
    
         ANS :'Hot spots' are places below the surface of the earth where hot molten magma settles after being pushed there by geological changes.


41. What is the temperature of hot-water geysers ?
    
         ANS :The temperature of hot-water geysers is about 700 °C.


42. Where are hot-water geysers found in Gujarat ?
    
         ANS :In gujarat, hot-water geysers are found at places like Unai, Tulsi Shyam in Saurashtra and at Lasundra and Tuva village in Godhra district.


43. What contributes to biomass ?
    
         ANS :Dead bodies of living organisms and their excretory products contribute to biomass.


44. Which process is basic in the formation of biomass ?
    
         ANS :Photosynthesis is the basic process in the formation of biomass.


45. Biomass is a direct form of solar energy. True or false ?
    
         ANS :No, this is a false statement.


46. Mention the route through which bioenergy is obtained.
    
         ANS :The route through which bioenergy is obtained is :
    
    Solar energy -> Photosynthesis -> Biomass -> Bioenergy.


47. How much energy of wood is used when burnt in traditional chulhas ?
    
         ANS :About 8 - 10 % of the energy of wood is used when burnt in traditional chulhas.


48. How is charcoal obtained from wood ?
    
         ANS :When wood is burnt with a limited supply of oxygen, it decomposes; volatile impurities and water are vaporised and charcoal is obtained as residue.


49. What does biogas contain ?
    
         ANS :Biogas contains about 65 - 75 % methane, 30 - 40 % carbon dioxide and traces of hydrogen, hydrogen sulphide and nitrogen.


50. Why is biogas traditionally called Gober gas ?
    
         ANS :Biogas is traditionally known as gober gas because it is obtained from the solid waste of animal dung, sewage,crop residue, vegetable wastes, poultry droppings as well as wastes from agro-based industries.


51. Mention two designs of biogas plants used in India.
    
         ANS :The two designs of biogas plants used in India are : (1) Fixed-dome type (2) Floating gas-holder type.


52. What is the full form of KVIC ?
    
         ANS :The full form of KVIC is Khadi and Village Industries Commission.


53. Where are the floating gas-holder type biogas plants used ?
    
         ANS :The floating gas-holder type biogas plants are used where animal dung is used to obtain biogas.


54. Where are the fixed-dome type biogas plants used ?
    
         ANS :The fixed-dome type biogas plants are used where human excreta and other wastes are used to obtain biogas.


55. Write the equation for the combustion of hydrogen.
    
         ANS :H₂ + 1/2 O₂ ---> H₂O + Heat


56. What is the main limitation of hydrogen as a source of energy ?
    
         ANS :The main limitation of hydrogen as a source of energy is that its combustion is explosive in nature.


57. When and where was the first coal mine in India dug /
    
         ANS :The first coal mine in India was dug in Raniganj of West Bengal in 1854 AD.


58. Mention the percentage of carbon in bituminous and anthracite coal.
    
         ANS :Bituminous coal contains about 78 - 87 % carbon and anthracite coal contains about 94 - 98 % carbon.


59. Mention one major use of coke.
    
         ANS :One major use of coke is as a reducing agent in metallurgy.


60. Where and when was the first oil well dug in India ?
    
         ANS :The first oil well in India was dug in 1867 AD in Makkum in Assam (This was the first oil well dug in Asia).


61. Where and when was the world's first oil well dug ?
    
         ANS :The world's first oil well was dug in 1859 AD in Pennsylvania (USA).


62. How much of total crude oil of India is obtained from Gujarat ?
    
         ANS :About 50% of total crude oil of India is obtained from Gujarat.


63. What are the usual height and diameter (width) of a fractional distillation tower ?
    
         ANS :The usual height and diameter of a fractional distillation tower are 31 m and 3 m, respectively.


64. What do petroleum gases mainly consist of ?
    
         ANS :Petroleum gases mainly consist of methane, ethane, propane and butane.


65. What is the full form of LPG ?
    
         ANS :The full form of LPG is Liquefied Petroleum Gas.


66. What is LPG ? OR What does LPG contain ?
    
         ANS :LPG is butane gas in compressed (liquefied) state.


67. What is added to LPG to detect leakage ?
    
         ANS :A foul smelling chemical (mercaptan) is added to LPG to detect leakage.


68. Mention the temperature range during which petrol (gasoline) is obtained.
    
         ANS :Petrol is obtained between the temperatures 40°C to 200 °C.


69. What is the proportion of petrol in petroleum ?
    
         ANS :The proportion of petrol in petroleum is about 45%.


70. During which temperature range is kerosene obtained from petroleum ?
    
         ANS :Kerosene is obtained from petroleum between 200°C to 300°C.


71. Who invented diesel ?
    
         ANS :Rudolf Diesel invented diesel.


72. How many carbon atoms are there in the hydrocarbon molecules of diesel ?
    
         ANS :There are 14 - 20 carbon atoms in the hydrocarbon molecules of diesel.


73. What is the boiling range of diesel ?
    
         ANS :The boiling range of diesel is 300°C to 350°C.


74. What is the boiling range of lubricating oil ?
    
         ANS :The boiling range of lubricating oil is 350°C to 400°C.


75. Mention the uses of lubricating oil.
    
         ANS :Lubricating oil is used for the preparation of wax and grease.


76. What is the main component of natural gas ?
    
         ANS :Methane is the main component of natural gas.


77. What is the full form of CNG ?
    
         ANS :The full form of CNG is Compressed Natural Gas.


78. Define combustion.
    
         ANS :Combustion is the process by which a substance burns and produces heat and/ or light.


79. Define Ignition temperature.
    
         ANS :The minimum temperature at which a substance starts burning in presence of oxygen is called its ignition temperature.


80. Define complete combustion.
    
         ANS :The process of combustion which takes place in sufficient supply of oxygen and releases maximum heat energy is called complete combustion.


81. Define incomplete combustion.
    
         ANS :The process of combustion which takes place in insufficient supply of oxygen and produces light due to yellow flame is called incomplete combustion.


82. Define Calorific value of fuel.
    
         ANS :The heat liberated by complete combustion of 1 gram of fuel is called the calorific value of that fuel.


83. Mention the calorific values of charcoal and wood.
    
         ANS :The calorific value of charcoal is 33 kJ/g and that of wood is 17 kJ/g.


84. Which fuel has the highest calorific value ? How much ?
    
         ANS :Hydrogen has the highest calorific value of 150 kJ/g.


85. What is the calorific value of methane ?
    
         ANS :The calorific value of methane is 55 kJ/g.


86. What is the calorific value of dung-cake ?
    
         ANS :The calorific value of dung-cake is 7 - 8 kJ/g.


87. Define : 1 atomic mass unit.
    
         ANS :One atomic mass is the mass equivalent to 1/12 of the mass of an unexcited C¹² isotope of carbon.


88. What is the rwlation between atomic mass unit (u) and kg ?
    
         ANS :1 u = 1.66 x 10^-27 kg.


89. Which are the units of mass and energy used in Solid-state physics ?
    
         ANS :In solid-state physics the unit of mass is atomic mass unit (u) and the unit of energy is 'electronvolt' (eV).


90. Define : Electronvolt.
    
         ANS :The change in the energy of an electron when it passes through two points having a potential difference of 1 V is called 1 electrovolt(eV) of energy.


91. What is the relation between the units of mass and energy ?
    
         ANS :The relation between the units of mass and energy is:
    
          1 u (mass) = 931.48 MeV (energy)
    
    [Here MeV stands for mega electronvolt]


92. What is meant by nucleons ?
    
         ANS :Nucleons mean protons and neutrons in the nucleus of an atom.


93. In the symbol _ZX^A, what are A and Z if X is an element ?
    
         ANS :A is the atomic mass (weight) and Z is the atomic number of element X.


94. If for an element X we write ₁₁X²³, then what is the number of neutrons in X ?
    
         ANS :The number of neutrons is 12 (23 - 11 =12).


95. Which are the elements called 'transuranic' ?
    
         ANS :Elements having atomic number Z greater than or equal to 92 are called transuranic elements.


96. What is nuclear fission ?
    
         ANS :A nuclear reaction in which a heavy nucleus (uranium for example) splits into two parts (products) which results in the emission of neutrons and energy is called nuclear fission.


97. In which elements does ₅₆Ba¹³⁹ get converted after the emission of β-particles ?
    
         ANS :₅₆Ba¹³⁹ get converted to ₅₇La¹⁴⁰ after the emission of β-particles.


98. When an atom of ₉₂U²³⁵ is bombarded by a neutron, a transuranic element is produced. True or false ?
    
         ANS :This is a false statement.


99. Mention the two categories of nuclear fission.
    
         ANS :Prompt fission and Delayed fission are the two categories of nuclear fission.


100. What is the range of atomic mass of two products obtained after nuclear fission ?
     
          ANS :The atomic mass of the heavy nucleus is in the range of 130 - 149 u and that of the light nucleus is in the range of 85 - 104 u.


101. What is spontaneous fission ?
     
          ANS :The process of fission of some heavy elements and isotopes without being bombarded by any projectile (neutrons) is called spontaneous fission.


102. How many nuclei of ₉₂U²³⁵ should be split by fission to produce 1 Ws (watt second) energy ?
     
          ANS :3.1 x 10¹⁰ nuclei/second should be split by fission to produce 1 Ws energy.


103. How much energy is produced by the fission of 1 kg of ₉₂U²³⁵ ?
     
          ANS :About 1000 MW-day energy is produced by the fission of 1 kg of ₉₂U²³⁵.


104. What is the full form of BARC ?
     
          ANS :The full form of BARC is Bhabha Atomic Research Centre.


105. Mention the locations of nuclear power plants established in India by Nuclear Power Corporation (of India) or NPC.
     
          ANS :NPC has established power plants in (i) Kakrapar in Gujarat (ii) Tarapore in Maharashtra (iii) Kota in Rajasthan (iv) Kalpakkam in Tamilnadu and (v) Narora in U.P.


106. What do we mean by chain reaction ?
     
          ANS :If in a reaction the products of one step result in producing the subsequent step of the reaction then that reaction is called CHAIN REACTION.OR A reaction that is self-sustaining as a result of the products of one step initiating a subsequent step is called CHAIN REACTION.


107. What are thermal neutrons ?
     
          ANS :Thermal neutrons are neutrons which are in thermal equilibrium with the environment at room temperature.


108. How much is the energy of a neutron released during fission ?
     
          ANS :The energy of a neutron released during fission is about 2 MeV.


109. How much is the energy of a thermal neutron ?
     
          ANS :The energy of a thermal neutron is about 0.04 eV.


110. What is a 'moderator' in a nuclear reaction ?
     
          ANS :Moderator is a substance that slows down neutrons released in a nuclear reactor, makinh them more likely to cause fission of ₉₂U²³⁵ and less likely to be absorbed by ₉₂U²³⁸. OR Moderator is a substance that lowers the energy of a neutron released during fission to thermal neutron energy range of 0.04 eV.


111. Mention two substances used as moderator in nuclear reactors.
     
          ANS :Graphite and heavy water are used as moderator in nuclear reactors.


112. Which coolants are used to cool down moderators ?
     
          ANS :Air, water, liquid sodium metal, etc. are used as coolants to cool down moderators.


113. Mention three isotopes of naturally occuring uranium.
     
          ANS :The isotopes of naturally occuring uranium are : ₉₂U²³⁴ ₉₂U²³⁵ and ₉₂U²³⁸.


114. Mention the proportion of different isotopes of uranium.
     
          ANS :The proportion of each isotope of uranium is : ₉₂U²³⁴ - 0.058%, ₉₂U²³⁵ - 0.715% and ₉₂U²³⁸ - 99.28%.


115. What is 'enrichment of uranium'?
     
          ANS :Enrichment of uranium is a specific process by which the proportion of ₉₂U²³⁵ (natural uranium) is increased substantially.


116. What is deuteron ?
     
          ANS :Deuteron is the nucleus of a heavy hydrogen atom which contains one proton and one neutron.


117. What is nuclear fusion ?
     
          ANS :A nuclear reaction in which two atomic nuclei combine to form a heavier nucleus with the release of a large amount of energy is called nuclear fusion.


118. What is 'missing mass'?
     
          ANS :Missing mass is the difference of the sum of the masses of fusing nuclei and the mass of the nucleus formed after fusion.


119. How much energy is produced when two ₁H² nuclei fuse to form ₂He³ and ₀H¹ ?
     
          ANS :When two ₁H² nuclei fuse to form ₂He³ and ₀H¹, 3.3 MeV energy is produced.


120. How is tritium obtained ?
     
          ANS :Tritium is obtained by bombardment of a neutron on an isotope of lithium.


121. What is plasma ?
     
          ANS :A highly ionised gas in which the number of moving negatively charged electrons is equal to the number of positively charged ions is called plasma.


122. What is thermonuclear fusion ?
     
          ANS :The fusion of two or more nuclei into one heavy nucleus due to the temperature being greater than 10⁶ K is called thermonuclear fusion.


123. Which process is used in the weapons of mass destruction like hydrogen bomb ?
     
          ANS :Uncontrolled thermonuclear fusion process is used in the weapons of mass destruction like hydrogen bomb.


124. What is the full form of IPR ?
     
          ANS :The full form of IPR is the Institute of Plasma Research.


125. What is the function of IPR (Institute of Plasma Research) ?
     
          ANS :IPR in Gujarat does research work on obtaining useful energy by Controlled thermonuclear fusion.


126. Mention where and when in Russia did nuclear explosion occur ?
     
          ANS :An explosion in a nuclear reactor occured in Chernobyl of Russia in 1986.(Chernobyl is now in Ukraine).


127. What is meant by nonrenewable source of energy ?
     
          ANS :A source of energy which takes very long time ( in terms of millions of years) for the formation and which cannot be regenerated in very short time is called a nonrenewable source of energy.


128. What are infrared rays ?
     
          ANS :Infrared rays are electromagnetic waves with wavelength more than 8000 A°.


129. 
     
          ANS :