Part-B (General Ability) NDA/NA Solved Paper 2017-I

General Knowledge

Total Questions: 50

1. Which one of the following devices changes low voltage alternating current to high voltage alternating current and vice versa?

Correct Answer: (c) Transformer
Solution:

A transformer is an electrical device which, by the principles of electromagnetic induction, transfers electrical energy from one electric circuit to another, without changing the frequency. It works on the 63. principle of mutual induction of two coils or Faraday Law's Of Electromagnetic induction. Transformers are used for increasing or decreasing the alternating voltages in electric power applications, and for coupling the stages of signal processing circuits.

2. An optical illusion which occurs mainly in deserts during hot summer is based on the principle of

Correct Answer: (d) Total internal reflection
Solution:

In physics, Total internal reflection (TIR), complete reflection of a ray of light within a medium such as water or glass from the surrounding surfaces back into the medium. Here, the ray of light continues to be
reflected within the medium (glass, water etc.) without being refracted off. TIR occurs not only with electromagnetic waves such as light waves and microwaves, but also with other types of waves, including sound and water waves.

3. At which place Earth's magnetic field becomes horizontal?

Correct Answer: (a) Magnetic meridian
Solution:

The magnetic meridian is an equivalent imaginary line connecting the magnetic south and north poles and can be taken as the horizontal component of magnetic force lines along the surface of the earth.

4. The speed of a car travelling on a straight road is listed below at successive intervals of 1 is:

Time(s)Speed(m/s)
00
12
24
36
48

Which of the following is/are correct?
The car travels
1. with a uniform acceleration of 2 m/s²
2. 16m in 4 s.
3. with an average speed of 4 m/s.
Select the correct answer using the code given below:

Correct Answer: (a) 1,2 and 3

5. The speed of a body that has Mach number more than 1 is

Correct Answer: (a) supersonic
Solution:

Mach number (M) is the ratio of the speed of a body to the speed of sound in the surrounding medium. If the body has Mach number greater than 1, the speed of the body is greater than the speed of the sound.
For Subsonic, M<1
For Supersonic, M>1
For Sonic, M=1
For Hypersonic, M>5

6. Molecules of which of the following has cage like structure?

1. Diamond
2. Graphite
3. Fullerenes
Select the correct answer using the code given below:

Correct Answer: (d) 3 only
Solution:

Fullerenes are molecules of carbon atoms. Fullerenes that have a cylindrical shape are called carbon nanotubes, because of their tubular shape and hollow center core. Their structures are based on hexagonal
rings of carbon atoms joined by covalent bonds. Some fullerenes include rings with five or seven carbon atoms.

7. Temporary hardness in water is due to which one of the following of Calcium and Magnesium?

Correct Answer: (a) Hydrogencarbonates
Solution:

Temporary hardness is due to the presence of calcium hydrogencarbonate Ca(HCO₃)2 (aq) and magnesium hydrogencarbonate Mg(HCO₃)2(aq). Both calcium hydrogencarbonate and magnesium hydrogencarbonate decompose when heated.

8. Stung by hairs of nettle leaves causes burning pain. This is due to the injection of

Correct Answer: (b) Methanoic acid
Solution:

Stung by hairs of nettle leaves causes burning pain. This is due to the injection of methanoic acid. Methanoic acid is the simplest carboxylic acid. It is also known as Fórmic acid. It's molecular formula is
HCOOH or CH2O2. It occurs naturally in a variety of sources, such as stinging ants, nettles, pine needles, and sweat.

9. Which one of the following elements is least reactive with water?

Correct Answer: (a) Lithium
Solution:

Lithium reacts intensely with water, forming lithium hydroxide and highly flammable hydrogen. The colourless solution is highly alkalic. The exothermal reactions lasts longer than the reaction of sodium and
water.

10. Rutherford's alpha-particle scattering experiment was responsible for the discovery of

Correct Answer: (c) Nucleus
Solution:

Rutherford's alpha-particle scattering experiment was responsible for the discovery of Nucleus.