General Knowledge Quiz for NDA 2020(Physics): 15th Feb 2020

Jai Hind Aspirants, Defence Adda is providing you all with this quiz on General Knowledge questions for NDA, CDS, AFCAT, CAPF and other Defence Examinations. The questions asked in General Knowlegde Section are based on the topics from History, Polity, Geography, Economics and General Science. We will provide you Important Questions on daily basis so that it becomes easy for you to crack written exam and get call letter for SSB Interview.

Q1. The density of water varies with temperature which helps the aquatic animals to live in cold water. At what temperature is the density of water maximum?
(a) 1°C
(b) 2°C
(c) 3°C
(d) 4°C

Q2. Who gave the first evidence of the big-bang theory?
(a) Edwin Hubble
(b) Albert Einstein
(c) S Chandrasekhar
(d) Stephen Hawking

Q3. A ray of light is incident on a plane mirror at an angle 30° with the normal at the point of incidence. The ray will be deviated from its incidence direction by what angle?
(a) 30°
(b) 60°
(c) 120°
(d) None of these

Q4. What would be the best choice for window material to keep the outside heat away?
(a) Single-pane glass
(b) Double-pane glass without a gap in between
(c) Double-pane glass with water filled in between
(d) Double-pane glass with air in between

Q5. Bar is a unit of which one of the following?
(a) Force
(b) Energy
(c) Pressure
(d) Frequency

Q6. On which one of the following conservative laws, does a rocket work?
(a) Mass
(b) Energy
(c) Linear momentum
(d) Angular momentum

Q7. Assertion (A): In a pressure cooker food is cooked above boiling point.
Reason (R): Boiling point of water increases as the pressure increases.
(a) Both A and R are true and R is the correct explanation of A
(b) Both A and R are true, but R is not the correct explanation of A
(c) A is true, but R is false
(d) A is false, but R is true

Q8.  The gas used in a refrigerator is
(a) Cooled down on flowing
(b) Heated up on flowing
(c) Cooled down when compressed
(d) Cooled down when expanded

Q9. The Celsius temperature is a/an
(a) Relative temperature
(b) Absolute temperature
(c) Specific temperature
(d) Approximate temperature

Q10. Light Emitting Diode (LED) converts
(a) Light energy into electrical energy
(b) Electrical energy into light energy
(c) Thermal energy into light energy
(d) Mechanical energy into electrical energy

Solutions

S1. Ans.(d)
Sol. Density of water is maximum at 4°C.

S2. Ans.(a)
Sol. Edwin Hubble gave the first evidence of the big-bang theory.

S3. Ans.(b)
Sol. By law of reflection, angle of incidence “i” is equal to angle of reflection “r”
Hence, Total deviation of ray = 30° + 30° = 60°

S4. Ans.(d)
Sol. To keep the outside heat away, windows of double-pane glass with air in between is the best choice because air is the bad conductor of heat.

S5. Ans.(c)
Sol. The SI unit of pressure is Pascal(Pa). The Bar is a metric unit of pressure. It is defined as exactly equal to 100,000 Pa (100 kPa).

S6. Ans.(c)
Sol. Rocket works on the principle of conservation of linear momentum and does so by expelling gas from its exhaust in a given a direction, which puts force on that gas.

S7. Ans.(a)
Sol. In a pressure cooker while cooking, the pressure increases due to which boiling point of water also increases as P ∝ T.

S8. Ans.(d)
Sol. This sudden opening allows the gas to expand, rapidly dropping the pressure and the temperature.

S9. Ans.(a)
Sol. Celsius, Fahrenheit scales are relative scales meaning their zeros have been arbitrarily defined. An absolute scale is one where zero is the lowest temperature possible. An absolute temperature scale with degree units the same as on Celsius scale is known as Kelvin scale and absolute scale using Fahrenheit degree units is known as Rankine scale.

S10. Ans.(b)
Sol. Light Emitting Diode (LED) is semiconductor device – a forward bias p-n junction diode which converts electrical energy into light energy.