UPSC Prelims 1999 · General Studies
Question 113: Science and Technology
Match List I (Quantity) with List II (Units) and select the correct answer using the codes given below the Lists: List I I. High speed II. Wavelength III. Pressure IV. Energy List II A) Mach B) Angstrom C) Pascal D) Joule Codes:
AnswerThe answer is (c).
High speed (of aircraft) is expressed as a Mach number, wavelength of light in angstroms, pressure in pascals and energy in joules. Mach number is a ratio of speed to the speed of sound, so strictly it is a measure rather than a unit, but it is the only fit for 'high speed' in the list. Remember: Mach for speed, angstrom for wavelength, pascal for pressure, joule for energy.
- I. High speed - Mach (A).
- II. Wavelength - angstrom (B).
- III. Pressure - pascal (C).
- IV. Energy - joule (D).
Why each option is right or wrong
- (a) Wrong. Swaps Mach and angstrom.
- (b) Wrong. Swaps pascal and joule.
- (c) Right. High speed-Mach, Wavelength-Angstrom, Pressure-Pascal, Energy-Joule.
- (d) Wrong. Makes both swaps.
Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 1999, General Studies. UPSC's own paper isn't online; the words are from a published compilation. The paper on upsc.gov.in.