Previous Year Questions General Science for CDS & CAPF: 8th October


Previous year questions must be prepared when it comes to the preparation of CDS & CAPF examinations. Defenceadda is providing you with the previous year questions of General Science Section.


Q1.  Which of the following statements about the commonly used automobile battery are true?
I. It is usually a lead-acid battery.
II. It has six cells with a potential of 2 V each.
III. Its cells work as galvanic cells while discharging power.
IV. Its cells work as electrolytic cells while recharging.
Select the correct answer using the codes given below
(a) I, II, III and IV
(b) I, II and III
(c) II and IV
(d) III and IV 

Q2. The light emitted by firefly is due to
(a) aAradioactive substance
(b) Chemiluminescence process
(c) A photoelectric process
(d) Burning of phosphorus

Q3. Which one of the following polymeric materials is used for making bullet proof jacket? 
(a) Nylon-6,
(b) Rayon
(c) Kevlar
(d) Dacron

Q4. The coil in a heater is made of 
(a) Nichrome
(b) Tungsten
(c) Copper
(d) Iron

Q5. Which among the following elements is abundant on the lunar surface and holds the potential to put an end to the energy crisis of the earth? 
(a) Helium-I
(b) Helium-II
(c) Helium-III
(d) Helium-IV

Q6. If a limestone piece is dipped in water, a bubble evolves. The bubbling is due to
(a) Hydrogen
(b) Oxygen
(c) Water vapour
(d) Carbon dioxide

Q7. Which one of the following chemicals is commonly used by farmers to destroy weeds? 
(a) DDT
(b) Malathion
(c) Methyl bromide
(d) 2, 4-D

Q8. Some statements about the benefits of organic farming are given below. Indicate whether they are true or false using the codes given below the statements: 
1. It reduces  emission.
2. It does not lead to toxic effect.
3. It improves the water-retention capacity of the soil.
Codes
(a)          1          2          3
              False    True    False
(b)          1          2          3
              True    False     False
(c)          1          2          3
              False    True    True
(d)          1          2          3
              False    False     True 

Q9. Match List I with List II and select the correct answer using the codes given below the Lists. 

List I

List II

(Alloy)

(Constituent)
A.
Solder
1
Iron and carbon
B.
Brass
2
Copper and zinc
C.
Bronze
3
Copper and tin
D.
Steel
4
Lead and tin

Codes
      A       B         C          D
(a) 1       2          3          4
(b) 4       2          3          1
(c) 1       3          2          4
(d) 4       3          2          1

Q10. Which one of the following is used as a mordant in dyeing and tanning industry?
(a) Magnesium oxide
(b) Magnesium carbonate
(c) Magnesium chloride
(d) Magnesium sulphate

SOLUTIONS

S1. Ans.(a)
Sol. Automobile batteries are usually lead-acid type, and are made of six galvanic cells in series to provide a 12- volts system. Each cell provides 2.1 volts for a total of 12.6 volts at full charge.
Lead-acid batteries are made up of plates of lead and separate plates of lead dioxide, which are submerged into an electrolyte solution of about 38% sulfuric acid and 62% water. This causes a chemical reaction that releases electrons, allowing them to flow through conductors to produce electricity. As the battery discharges to produce electricity.

S2. Ans.(b)
Sol. Light production in fireflies is due to a type of chemical reaction called bioluminescence. This process occurs in specialized light-emitting organs, usually on a firefly’s lower abdomen. The enzyme luciferase acts on the luciferin, in the presence of magnesium ions, ATP, and oxygen to produce light.

S3. Ans.(c)
Sol. Kevlar, a polymeric material is used for making bullet proof jacket.

S4. Ans.(a)
Sol. The coil in a heater is made up of nichrome because its melting point and resistivity are high.

S5. Ans.(c)
Sol. Helium-III is abundant on the lunar surface and holds the potential to put an end to the energy crisis of the Earth.

S6. Ans.(d)
Sol. When limestone piece is dipped in water, the bubbles evolve due to evolution of carbon dioxide.
 
S7. Ans.(d)
Sol. 2, 4-D (2, 4-dichlorophenoxy acetic acid) is used to destroy weeds.

S8. Ans.(c)
Sol. Organic farming is the of agriculture that relies on crop rotation, green manure, compost, biological pest control and mechanical cultivation to maintain soil productivity and control pests. It does not reduce  emission. It does not lead to toxic effect. It improves the water-retention capacity of the soil.

S9. Ans.(b)
Sol.
(Alloy)                                    (Constituent)
Solder                                     Lead and tin
Brass                                      Copper and zinc
Bronze                                    Copper and tin
Steel                                        Iron and carbon

S10. Ans.(d)
Sol. Magnesium sulphate (MgS ) is used as a mordant in dyeing and tanning industry.




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