NDA 2019 Previous Year GK Questions with Answers

The correct answer is A, 318 K. A reading of 113 on the Fahrenheit scale works out to 45 degrees Celsius, and adding 273 to that gives about 318 K. Fahrenheit is turned into Celsius with the relation C = (F - 32) x 5/9, so (113 - 32) x 5/9 = 81 x 5/9 = 45 degrees Celsius. The Kelvin scale begins at absolute zero and its degree is the same size as the Celsius degree, so K = C + 273.15, which makes 45 degrees Celsius equal to 318.15 K, written as 318 K in the options. Keep in mind that 0 degrees Celsius is 273 K, and that water freezes at 32 F and boils at 212 F. B is wrong because 45 is the Celsius value and not the Kelvin value. C is wrong because that figure comes from an incomplete conversion instead of the full formula. D is wrong because it adds 273 to the wrong Celsius value. Exam tip: do it in two steps, Fahrenheit to Celsius first, then add 273.

The correct answer is C, because the Suez Canal has no locks at all. It is a sea level canal: the Mediterranean and the Red Sea stand at almost the same height, so ships sail straight through without being raised or lowered. The canal, about 193 km long, was built under Ferdinand de Lesseps and opened in November 1869 across the Isthmus of Suez in Egypt, separating Africa from Asia. Egypt nationalised it in 1956. Options A, B and D all state facts, so none of them is the answer: the canal did open in 1869, it does join the Mediterranean to the Red Sea through the Gulf of Suez, and it did shorten the voyage from Europe to India by thousands of kilometres, ending the long route round the Cape of Good Hope. Exam tip: Suez is a lock free canal; the Panama Canal is the one with locks, because Gatun Lake lies well above sea level.

The correct answer is B, the amplitude of the sound waves. Amplitude is the maximum displacement of a particle of the medium from its rest position, and the energy carried by a wave increases with the square of the amplitude. A larger amplitude therefore delivers more energy to the ear and is heard as a louder sound. Loudness is measured in decibel.

Option A, the velocity of the wave, is fixed by the medium and its temperature; a loud and a soft sound in the same room travel at exactly the same speed. Option C, frequency, decides pitch, that is whether the sound is shrill or flat, and not how loud it is; turning up the volume of a ringtone does not change its frequency. Option D combines two quantities that both govern properties other than loudness, so it is wrong for the same reasons.