Previous Year Questions General Science for CDS & CAPF: 5th 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.  The focal length of convex lens is  
(a) The same for all colours 
(b) Shorter for blue light than for red 
(c) Shorter for red light than for blue 
(d) Maximum for yellow light 

Q2. The pressure of a fluid varies with depth h as P = P0 + ρgh, where ρ is the fluid density. This expression is associated with 
(a) Pascal’s law 
(b) Newton’s law 
(c) Bernoulli’s principle 
(d) Archimede’s principle 

Q3. The time period of a simple pendulum having a spherical wooden bob is 2 s. If the bob is replaced by a metallic one twice as heavy, the time period will be 
(a) More than 2 s 
(b) 2 s 
(c) 1 s 
(d) Less than 1 s 

Q4. A liquid is kept in a regular cylindrical vessel upto a certain height. If this vessel is replaced by another cylindrical vessel having half the area of cross-section of the bottom, the pressure on the bottom will  
(a) Remain unaffected 
(b) Be reduced to half the earlier pressure 
(c) Be increased to twice the earlier pressure 
(d) Be reduced to one-fourth the earlier pressure 

Q5. In SONAR, we use 
(a) Ultrasonic waves 
(b) Infrasonic waves 
(c) Radio waves 
(d) Audible sound waves 

Q6. Two identical piano wires have same fundamental frequency when kept under the same tension. What will happen if tension of one of the wire is slightly increased and both the wires are made to vibrate simultaneously?  
(a) Noise 
(b) Beats 
(c) Resonance 
(d) Non-linear effects 

Q7. After rising a short distance the smooth column of smoke from a cigarette breaks up into an irregular and random pattern. In a similar fashion, a stream of fluid flowing past an obstacle breaks up into eddies and vortices which give the flow irregular velocity components transverse to the flow irregular velocity components transverse to the flow direction. Other examples include the wakes left in water by moving ships the sound produced by whistling and by wind instruments. These examples are the results of  
(a) Laminar flow of air 
(b) Streamline flow of air 
(c) Turbulent flow of air 
(d) Viscous flow at low speed 

Q8. Which one among the following correctly defines a unit magnetic pole in SI units?  
(a) 1 foot from an equal and a similar poled repels it with a force of 1 pound 
(b) 1 m from an equal and a similar pole repels it with a force of 1 N 
(c) 1 cm from an equal and a similar pole repels it with a force of 1 dyne 
(d) 1 metre from an equal and a similar pole repels it with a force of 1 N/m²

Q9. Before X-ray examination (coloured X-ray) of the stomach, patients are given suitable salt of barium because  
(a) Barium salts are white in colour and this helps stomach to appear clearly 
(b) Barium is a good absorber of X-rays and helps stomach to appear clearly 
(c) Barium salts are easily available 
(d) Barium allows X-rays to pass through the stomach 

Q10. The best colours for a sun umbrella will be 
(a) Black on top and red on inside 
(b) Black on top and white on inside 
(c) Red on top and black on inside 
(d) White on top and black on inside 


SOLUTIONS
S1. Ans.(b)
Sol. The focal length of a convex lens is shorter for blue light than for red. 

S2. Ans.(a)
Sol. Pascal’s principle, also called Pascal’s law, in fluid (gas or liquid) mechanics, statement that, in a fluid at rest in a closed container, a pressure change in one part is transmitted without loss to every portion of the fluid and to the walls of the container. 

S3. Ans.(b)
Sol. Time period of a simple pendulum 
T = 2π √(l/g) depends on its length 'l' and acceleration due to gravity ‘g’ and independent of mass of the bob. 

S4. Ans.(a)
Sol. Pressure exerted by the fluid column depends on height (h), density ρ and acceleration due to gravity (g). 
P = hρg 
i.e. independent of area of cross-section of the vessel. 

S5. Ans.(a)
Sol. Sonar (sound navigation and ranging) is a technique that uses sound propagation to navigate (usually under water, as in submarine navigation), communicate with or detect objects on or under the surface of the water, such as the vessels as ultrasonic waves which is used having very high frequency>20,000 Hz.

S6. Ans.(b)

S7. Ans.(c)
Sol. Turbulent flow is accompanied by random, irregular, local circular currents called vortices. 

S8. Ans.(b)

S9. Ans.(b)
Sol. Barium is a good absorber of X-rays and helps stomach to appear clearly. 

S10. Ans.(d)
Sol. As white colour reflects all the components of white light and black colour absorbs all the components of white light. So, the best  colours for a sun umbrella, white on top and black on inside. 



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