NDA/NA SOLVED PAPER 2015-I (GENERAL KNOWLEDGE)

Total Questions: 100

1. (Questions 1-8) Statement I and Statement II. You are to examine these two statements carefully and select the answers to these items using the code given below :

Statement I: Growth of plants is smooth with a complete fertilizer.
Statement II: A complete fertilizer always contains N, P, K.

Correct Answer: (a) Both the statements are individually true and Statement II is the correct explanation of Statement I
Solution:Complete fertilisers are usually defined as fertilizers containing all three macronutrients: nitrogen, phosphorus and potassium (N, P, K)

2. Select the answers to these items using the code given below :

Statement I: The granules of modern gunpowder (also called black powder) are typically coated with Graphite.
Statement II: Graphite prevents the build-up of electrostatic charge.

Correct Answer: (a) Both the statements are individually true and Statement II is the correct explanation of Statement I
Solution:Commercial black powder looks black because the little lumps of the stuff are coated with graphite. In the manufacturing process, the powder's mixed with water or some other liquid binder, pressed into cakes and dried, then crushed and screened into powders of various particle size, larger particles producing a slower burn. The graphite serves no chemical purpose, but it lubricates the particles, and also makes the bulk powder electrically conductive enough that it is unlikely to initiate proceedings unexpectedly because of a static-electricity spark.

3. Select the answers to these items using the code given below :

Statement I: Colour of nitrogen dioxide changes to colourless at low temperature.
Statement II: At low temperature Nitrogen tetroxide (N₂O₄) is formed which is colourless.

Correct Answer: (a) Both the statements are individually true and Statement II is the correct explanation of Statement I
Solution:NO₂ exists in equilibrium with the colourless gas dinitrogen tetroxide (N₂O₄). At higher temperature NO₂ is favoured while at low temperature N₂O₄ predominates.

4. Select the answers to these items using the code given below :

Statement I: Diamond is very bright.
Statement II: Diamond has very low refractive index.

Correct Answer: (c) Statement I is true but Statement II is false
Solution:The refractive index of diamond is very high (2.417).

5. Select the answers to these items using the code given below :

Statement I: Oxygen gas is easily produced at a faster rate by heating a mixture of potassium chlorate and manganese dioxide than heating potassium chlorate alone.
Statement II: Manganese dioxide acts as a negative catalyst.

Correct Answer: (c) Statement I is true but Statement II is false
Solution:Heating a mixture of potassium chlorate and manganese dioxide produces oxygen gas and manganese dioxide acts as a positive catalyst.

6. Select the answers to these items using the code given below :

Statement I: A body weighs less on a hill top than on earth's surface even though its mass remains unchanged.
Statement II: The acceleration due to gravity of the earth decreases with height.

Correct Answer: (a) Both the statements are individually true and Statement II is the correct explanation of Statement I
Solution:Mass is an invariant quantity. Acceleration due to gravity (g) decreases with altitude as one rises above. the Earth's surface because greater altitude means greater distance from the Earth's centre.
Weight, w = mass (m) × acc. due to gravity (g)

Hence body weighs less on hill top than on earth's surface.

7. Select the answers to these items using the code given below :

Statement I: While putting clothes for drying up, we spread them out.
Statement II: The rate of evaporation increases with an increase in surface area.

Correct Answer: (a) Both the statements are individually true and Statement II is the correct explanation of Statement I
Solution:An increased surface area means that more liquid will be exposed to air at one time, and therefore, more water can evaporate in a given time period.

8. Select the answers to these items using the code given below :

Statement I: Due to diffused of irregular reflection of light, a closed room gets light even if no direct sunlight falls inside the room.
Statement II: Irregular reflection, where the reflected rays are not parallel, does not follow the laws of reflection.

Correct Answer: (c) Statement I is true but Statement II is false
Solution:Diffuse reflection is the reflection of light from a rough surface such that an incident rays are reflected at many angles rather than at just one angle. In diffused reflection reflect rays are not parallel but obey laws of reflection.

9. Ultrasonic waves of frequency 3 × 10⁵ Hz are passed through a medium where speed of sound is 10 times that in air (Speed of sound in air is 300 m/s). The wavelength of this wave in that medium will be of the order of

Correct Answer: (a) 1 cm
Solution:

10. Ifradius of the earth were to shrink by 1%, its mass remaining the same, g would decrease by nearly

Correct Answer: (b) 2%
Solution:If the radius of the earth were to shrink by one percent, mass remaining the same, the value of g will increase by 2%.
g = GM / R²
If mass remains constant, then g ∝ 1 / R² % increase in g = 2 (% decrease in R)= 2 × 1 % = 2 %
Therefore value of g will increase by 2%.